WO2022074363A1 - A platinum alloy composition - Google Patents
A platinum alloy composition Download PDFInfo
- Publication number
- WO2022074363A1 WO2022074363A1 PCT/GB2021/052542 GB2021052542W WO2022074363A1 WO 2022074363 A1 WO2022074363 A1 WO 2022074363A1 GB 2021052542 W GB2021052542 W GB 2021052542W WO 2022074363 A1 WO2022074363 A1 WO 2022074363A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- weight percent
- alloy composition
- tin
- indium
- platinum
- Prior art date
Links
- 239000000203 mixture Substances 0.000 title claims abstract description 136
- 229910001260 Pt alloy Inorganic materials 0.000 title claims abstract description 105
- 239000011135 tin Substances 0.000 claims abstract description 266
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 243
- 239000000956 alloy Substances 0.000 claims abstract description 243
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 136
- 239000011572 manganese Substances 0.000 claims abstract description 132
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 131
- 229910052718 tin Inorganic materials 0.000 claims abstract description 109
- 229910052738 indium Inorganic materials 0.000 claims abstract description 106
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 105
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 101
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims abstract description 100
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims abstract description 99
- 229910052733 gallium Inorganic materials 0.000 claims abstract description 98
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims abstract description 90
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 61
- 239000010931 gold Substances 0.000 claims abstract description 58
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 58
- 239000010948 rhodium Substances 0.000 claims abstract description 55
- 239000010949 copper Substances 0.000 claims abstract description 54
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 51
- 229910052742 iron Inorganic materials 0.000 claims abstract description 48
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 46
- 239000010941 cobalt Substances 0.000 claims abstract description 46
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 46
- 229910052802 copper Inorganic materials 0.000 claims abstract description 45
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 43
- 229910052741 iridium Inorganic materials 0.000 claims abstract description 43
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims abstract description 43
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229910052737 gold Inorganic materials 0.000 claims abstract description 42
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910052707 ruthenium Inorganic materials 0.000 claims abstract description 36
- 229910052702 rhenium Inorganic materials 0.000 claims abstract description 33
- WUAPFZMCVAUBPE-UHFFFAOYSA-N rhenium atom Chemical compound [Re] WUAPFZMCVAUBPE-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 33
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims abstract description 33
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims abstract description 17
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 15
- 239000012535 impurity Substances 0.000 claims abstract description 9
- 238000007711 solidification Methods 0.000 claims description 91
- 230000008023 solidification Effects 0.000 claims description 91
- 238000005266 casting Methods 0.000 claims description 40
- 238000005275 alloying Methods 0.000 claims description 26
- 239000007788 liquid Substances 0.000 claims description 11
- 239000006104 solid solution Substances 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 7
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- 239000004411 aluminium Substances 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 239000010936 titanium Substances 0.000 claims description 3
- 238000002844 melting Methods 0.000 description 77
- 230000008018 melting Effects 0.000 description 77
- 239000012071 phase Substances 0.000 description 47
- 238000005336 cracking Methods 0.000 description 26
- 238000007792 addition Methods 0.000 description 13
- 230000015572 biosynthetic process Effects 0.000 description 13
- 229910000765 intermetallic Inorganic materials 0.000 description 13
- 238000001556 precipitation Methods 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 12
- 238000004364 calculation method Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- 238000011049 filling Methods 0.000 description 9
- 239000010437 gem Substances 0.000 description 9
- 229910001751 gemstone Inorganic materials 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000013461 design Methods 0.000 description 7
- 239000011159 matrix material Substances 0.000 description 7
- 239000002244 precipitate Substances 0.000 description 7
- 230000002411 adverse Effects 0.000 description 6
- 239000000155 melt Substances 0.000 description 5
- 230000000875 corresponding effect Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 239000000102 jewellery alloy Substances 0.000 description 4
- 238000003754 machining Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 230000001603 reducing effect Effects 0.000 description 4
- 238000005204 segregation Methods 0.000 description 4
- 239000002893 slag Substances 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000010587 phase diagram Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 206010020751 Hypersensitivity Diseases 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 208000026935 allergic disease Diseases 0.000 description 1
- 230000007815 allergy Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000000113 differential scanning calorimetry Methods 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 230000005307 ferromagnetism Effects 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 238000010801 machine learning Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 229910052706 scandium Inorganic materials 0.000 description 1
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000010187 selection method Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000007619 statistical method Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 229910000601 superalloy Inorganic materials 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C5/00—Alloys based on noble metals
- C22C5/04—Alloys based on a platinum group metal
-
- A—HUMAN NECESSITIES
- A44—HABERDASHERY; JEWELLERY
- A44C—PERSONAL ADORNMENTS, e.g. JEWELLERY; COINS
- A44C27/00—Making jewellery or other personal adornments
- A44C27/001—Materials for manufacturing jewellery
- A44C27/002—Metallic materials
- A44C27/003—Metallic alloys
Definitions
- the present invention relates to a platinum alloy composition, in particular a platinum alloy composition for use in jewellery and an alloy composition for jewellery with improved castability and to jewellery.
- alloying elements can adversely affect the castability of the material.
- additions of certain elements to Pt will increase the overall melting temperature of the alloy.
- a higher melting temperature will increase the reaction of molten metal with the mould material during the casting process and reduce surface quality.
- a higher melting temperature may also result in reduced alloy fluidity during casting as it may be difficult to achieve sufficient 'superheat' prior to casting given the already high melting point of pure platinum.
- the present invention provides a platinum alloy composition consisting, in weight percent, of: 0.0 to 10.0 gold, 0.0 to 5.0 cobalt, 0.0 to 10.0 copper, 0.0 to 7.0 iron, 0.0 to 4.0 gallium, 0.0 to 3.0 indium, 0.0 to 5.0 iridium, 0.0 to 10.0 manganese, 0.0 to 7.0 nickel, 0.0 to 15.0 palladium, 0.0 to 5.0 rhenium, 0.0 to 5.0 rhodium, 0.0 to 10.0 ruthenium, 0.0 to 3.0 tin, 85.0 or more platinum and incidental impurities, wherein two or more of gallium, indium and tin are present in an amount of 0.1 or more, wherein the following equation is satisfied in which WCo, WCu, WFe, WGa, WIn, WNi, Wpd, WSn, WRh, WIr, WAu, WRu , WRe , and WMn are the weight percent of cobalt, copper, iron, gall
- Such an alloy is suitable for use in jewellery, has a melting point significantly below that of elemental platinum and lower than that of prior art alloys and has increased hardness compared to elemental platinum and several commonly used platinum alloys.
- the alloys according to the present invention are well suited for the fabrication of jewellery and other ornamental articles because they exhibit superior castability and mechanical properties relative to a large number of benchmarks.
- the alloys have a low solidification range and lower prevalence of intermetallics making them suitable for casting and subsequent forming without the need for heat treatment.
- the platinum alloy composition consists, in weight percent, of 90.0 or more platinum or sum of platinum and iridium, preferably 95.0 or more platinum or sum of platinum and iridium.
- Such an alloy meets the 900Pt or 950Pt standard for platinum jewellery respectively.
- the platinum alloy composition satisfies the following equation in which W Co , W Cu , W Fe , W Ga , W In , W Ni , W Pd , W Sn , W Rh , W Ir , W Au , W Ru , W Re , and W Mn are the weight percent of cobalt, copper, iron, gallium, indium, nickel, palladium, tin, rhodium, iridium, gold, ruthenium, rhenium, and manganese in the alloy respectively
- Such an alloy has superior hardness making it suitable for jewellery.
- the platinum alloy composition satisfies the following equation in which W Co , W Cu , W Fe , W Ga , W In , W Ni , W Pd , W Sn , W Rh , W Ir , W Au , W Ru , W Re , and W Mn are the weight percent of cobalt, copper, iron, gallium, indium, nickel, palladium, tin, rhodium, iridium, gold, ruthenium, rhenium, and manganese in the alloy respectively
- the platinum alloy composition satisfies the following equation in which W co , W cu , W Fe , W Ga , W In , W Ni , W Pd , W Sn , W Rh , Wi Ir W Au , W Ru , W Re , and W Mn are the weight percent of cobalt, copper, iron, gallium, indium, nickel, palladium, tin, rhodium, iridium, gold, ruthenium, rhenium, and manganese in the alloy respectively
- Such an alloy has superior resistance to hot cracking.
- the platinum alloy composition satisfies the following equation in which W co , W Cu , W Fe , W Ga , W In , W Ni , W Pd , W Sn , W Mn , W Ru , W Ir , W Rh , W Au and W Re are the weight percent of cobalt, copper, iron, gallium, indium, nickel, palladium, tin, manganese, ruthenium, iridium, rhodium, gold and rhenium in the alloy respectively
- Such an alloy has a lower melting temperature and therefore reacts less with mould walls during casting and so has superior surface quality.
- the platinum alloy composition consists, in weight percent, of 5.0 or less nickel. Such an alloy will be unlikely to cause a reaction on human skin contact.
- the platinum alloy composition consists, in weight percent, of 3.0 or less iridium. Such an alloy has reduced cost.
- the platinum alloy composition consists, in weight percent, of 3.0 or less rhodium. Such an alloy has reduced cost. In an embodiment the platinum alloy composition consists, in weight percent, of 5.0 or less ruthenium, preferably 3.0 or less ruthenium. Such an alloy will have superior casting properties.
- the platinum alloy composition consists, in weight percent, of 3.0 or less rhenium. Such an alloy will have a lower melting temperature leading to superior casting properties.
- the platinum alloy satisfies the following equation in which W Ga , W In , and W sn are the weight percent of gallium, indium, and tin in the alloy W sn + W In + W Ga ⁇ 0.40.
- W Ga , W In , and W sn are the weight percent of gallium, indium, and tin in the alloy W sn + W In + W Ga ⁇ 0.40.
- Such an alloy will have a higher hardness
- the platinum alloy composition consists, in weight percent, of 2.5 or less indium, preferably 2.0 or less indium. Such an alloy will produce fewer intermetallic phases on cooling and has a lower solidification range.
- platinum alloy composition of any of the preceding claims consisting, in weight percent, of 2.5 or less tin, preferably 2.0 or less tin.
- Such an alloy will produce fewer intermetallic phases on cooling and has a lower solidification range.
- the alloy composition comprises 0.55 or more volume fraction solid solution FCC gamma phase, preferably 0.6 or more volume fraction gamma phase, more preferably 0.7 or more volume fraction gamma phase, even more preferably 0.8 or more volume fraction gamma phase, most preferably 0.9 or more volume fraction gamma phase.
- Such an alloy is desirable as the risk of reduced ductility is lowered.
- the alloy composition has a solidification range of 200 °C or less, preferably wherein the alloy composition has a solidification range of 150 °C or less, more preferably wherein the alloy composition has a solidification range of 125 °C or less, more preferably wherein the alloy composition has a solidification range of 100 °C or less, even more preferably wherein the alloy composition has a solidification range of 75 °C or less, most preferably wherein the alloy composition has a solidification range of 50 °C or less.
- Such an alloy will have superior casting properties with lower propensity for pore formation.
- platinum alloy composition of any preceding claim wherein at least two, preferably at least three, elements selected from the following list are present: gold, cobalt, copper, iron, gallium, indium, iridium, manganese, nickel, palladium, rhenium, rhodium, ruthenium, tin.
- elements selected from the following list are present: gold, cobalt, copper, iron, gallium, indium, iridium, manganese, nickel, palladium, rhenium, rhodium, ruthenium, tin.
- Such alloys have been shown to exhibit the best combination of properties sought in this application.
- indium and tin are present in an amount of 0.1 or more in the platinum alloy composition.
- Such an alloy has reduced intermetallic precipitation.
- Such an alloy is likely to have a lower solidification range.
- the platinum alloy composition satisfies the following equation in which W Co , W Fe , W Ni , and W Pd are the weight percent of cobalt, iron, nickel, and palladium in the alloy respectively
- platinum alloy composition of any of the preceding claims consisting, in weight percent, of 5.0 or less gold, preferably 3.0 or less gold.
- Such an alloy has reduced solidification range.
- the platinum alloy composition of any of the preceding claims consisting, in weight percent, of 9.0 or less copper, preferably 8.0 or less copper.
- Such an alloy has improved castability as formation of slag during melting for casting is less likely and the alloy has a lower solidification range.
- the platinum alloy composition consists, in weight percent, of 2.0 or less gallium, preferably 1.5 or less gallium.
- Such an alloy has a lower solidification range and lower chance of precipitation of intermetallic phases.
- Such an alloy has reduced melting temperature.
- Such an alloy will have superior ductility as the formation of large brittle grains made of intermetallic phases on solidification will be avoided.
- the platinum alloy composition consists, in weight percent, 0.0 to 1.0 total sum weight percent of gold, iridium, manganese, rhenium, rhodium, and ruthenium.
- Such an alloy is preferred because it is possible to achieve favourable properties in terms of harness and castability (e.g. low melting point, low solidification range and/or low hot cracking propensity) whilst maintaining a high platinum content.
- the platinum alloy composition satisfies the following equation in which W co , W cu , W Fe , W Ga , W In , W Ni , W Pd , W Sn , W Mn , W Ru , W Ir , W Rh , WAu and WRe are the weight percent of cobalt, copper, iron, gallium, indium, nickel, palladium, tin, manganese, ruthenium, iridium, rhodium, gold and rhenium in the alloy respectively
- Such an alloy has lowered solidification range leading to better castability, particularly less porosity on casting.
- the platinum alloy composition satisfies the following equation in which Wc 0 , W Cu , W Fe , W Ni , and W P d are the weight percent of cobalt, copper, iron, nickel and palladium in the alloy W Co + W Pd + W Fe + W Ni + W Cu ⁇ 2.0.
- Wc 0 , W Cu , W Fe , W Ni , and W P d are the weight percent of cobalt, copper, iron, nickel and palladium in the alloy W Co + W Pd + W Fe + W Ni + W Cu ⁇ 2.0.
- Such an alloy has a lower melting point without dramatic increase in solidification range.
- the two or more of gallium, indium and tin are present in an amount of 0.25 or more, preferably wherein the two or more of gallium, indium and tin are present in an amount of 0.5 or more.
- Such an alloy has increased hardness.
- the platinum alloy composition satisfies the following equation in which W co , W Fe , and W Ni , are the weight percent of cobalt, iron, and nickel in the alloy 3.0 ⁇ W Co + W Fe + W Ni ⁇ 4.5.
- Such an alloy particularly in the absence of copper and palladium has reduced melting point without a corresponding increase in solidification range.
- the platinum alloy composition satisfies the following equation in which W Ga , W In , and W Sn , are the weight percent of gallium, indium and tin in the alloy 0.4 ⁇ Wc a + W In + Ws n ⁇ 2.2. This gives an alloy with superior hardness without a corresponding increase in solidification range.
- the platinum alloy composition is made up of 95 weight percent or more of platinum and satisfies the following equation in which W co , W Fe , and W Ni , are the weight percent of cobalt, iron, and nickel in the alloy 3.0 ⁇ W Co + W Fe + W Ni ⁇ 4.5 as well as the following equation in which W Ga , W In , and W Sn , are the weight percent of gallium, indium and tin in the alloy 0.4 ⁇ W Ga + W In + W Sn ⁇ 2.2.
- W co , W Fe , and W Ni are the weight percent of cobalt, iron, and nickel in the alloy 3.0 ⁇ W Co + W Fe + W Ni ⁇ 4.5 as well as the following equation in which W Ga , W In , and W Sn , are the weight percent of gallium, indium and tin in the alloy 0.4 ⁇ W Ga + W In + W Sn ⁇ 2.2.
- the two or more of gallium, indium and tin are indium and gallium and the following equation is satisfied in which W Ga and W In , are the weight percent of gallium and indium in the alloy 0.5 W In ⁇ W Ga ⁇ 1.5 W In .
- Such an alloy has reduced chance of intermetallic precipitation.
- the two or more of gallium, indium and tin are tin and gallium and the following equation is satisfied in which W Ga and W Sn , are the weight percent of gallium and tin in the alloy
- the two or more of gallium, indium and tin are indium and tin and the following equation is satisfied in which W In , and W Sn , are the weight percent of indium and tin in the alloy 0.5 W In ⁇ W Sn ⁇ 1.5 W In .
- the two or more of gallium, indium and tin are indium, tin and gallium and the following equations are satisfied in which W Ga , W In , and W Sn , are the weight percent of gallium, indium and tin in the alloy 0.3 W In ⁇ W Ga ⁇ 1.3 W In ; 0.3 W Sn ⁇ W Ga ⁇ 1.3 W Sn ; 0.3 W In ⁇ W Sn ⁇ 1.3 W In .
- Such an alloy has reduced chance of intermetallic precipitation.
- Figure 1 shows predicted hardness values vs the melting point index for a range of compositions.
- Benchmark jewellery alloys are overlaid for comparison.
- the hatched polygon shows the improvement achievable over the benchmark alloys with the present invention.
- Figure 2 is a comparison of gamma prime volume fraction and melting point index for a range of compositions the hatched polygon shows a preferred area and some benchmark alloys are shown too.
- Figure 3 shows predicted hot cracking index vs the melting point index for a range of compositions.
- Benchmark jewellery alloys are overlaid for comparison.
- the hatched polygon shows a preferred area.
- Figure 4 shows predicted solidification range values vs the melting point index for a range of compositions. Benchmark jewellery alloys are overlaid for comparison. The hatched polygon shows a preferred area.
- Figure 5 shows the amount of hard intermetallic phases (in atomic percent) formed due to segregation during the solidification of platinum alloys containing 5.0 wt% of cobalt and 4.9X wt% where X is any combination of gallium, indium and tin which adds up to 1. The values were obtained by Scheil-Gulliver thermodynamic calculations which is a widely accepted way of modelling the fraction of various phases in the as-cast state.
- terminal intermetallics are undesirable as they reduce the ductility of the alloy and may cause machining and forming issues.
- the amount of terminal intermetallics is lowest when all three elements (gallium, indium and tin) are present.
- Figure 6 shows the shape of test castings.
- Figure 7 shows experimental results of the test castings for three alloy compositions showing hardness, grid fill and porosity.
- Figure 8 compares the machinability of an alloy of the present invention with a comparative example.
- Figure 9 compares castability of an alloy of the present invention with a comparative example.
- the hardness of platinum alloys is derived from two chemically determined mechanisms:
- Precipitation hardening - for elements added which are outside the solubility limit of platinum secondary phases may occur. These phases increase the alloys resistance to deformation.
- Hot tearing - Alloys which have a very wide solidification temperature range suffer from a combination of increasing thermal stress arising from the reducing temperature combined with limited mechanical strength due to liquid films between growing grains. The combination of increasing stress and poor mechanical strength leads to tearing of the metal at high temperature resulting in a scrapped component.
- Superior castability is achieved in the present invention by optimising several material properties, reflected in merit indices. These include the melting point index and optionally the hot cracking index. Their values are correlated to the risk of typical casting defects: shrinkage porosity, gas porosity, formation of inclusions, poor surface finish and poor form filling.
- the alloys in the invention have a tunable hardness and a hardness of 150 HV or more can be achieved, offering the potential to trade off the ease of formability for improved wear resistance, depending on the application.
- the as-cast microstructures of the alloys can have sufficient ductility which facilitates further processing steps such as gem setting.
- the inventors have determined that this can be achieved if the composition has at least 0.3 volume fraction of ductile gamma Pt matrix at 1000 °C. A higher level of gamma phase is desirable as this further increases the ductility.
- the as-cast microstructure may not be the same as the equilibrium microstructure at 1000 °C.
- a modelling-based approach used for the isolation of new grades of platinum alloys addressing at least some of the above issues is described here.
- This approach utilises a framework of computational materials models combined with machine learning to estimate design-relevant properties across a very broad compositional space.
- this alloy design tool allows the so- called inverse problem to be solved; identifying optimum alloy compositions that best satisfy a specified set of design constraints.
- the first step in the design process is the definition of an elemental list along with the associated upper and lower compositional limits.
- the compositional limits for each of the elemental additions considered in this invention - referred to as the "alloy design space" - are detailed in Table 1. These limits were selected by the inventors on the basis of the explanations given below. Some of the insights are from metallurgical experience whilst others, such as the effects on melting point, castability of the platinum alloys and presence of intermetallic phases have been established by the inventors based on thermodynamic calculations described below on a wider range of compositions than set out in Table 1.
- the minimum amount of platinum in the alloys in weight percent was set to 85.0 as this is a minimum acceptable amount of platinum for jewellery applications.
- any iridium content in a platinum alloy is considered equivalent to platinum meaning that the platinum content of an alloy is considered as being equivalent the sum of platinum and iridium.
- the minimum amount of platinum (or sum of platinum and iridium) in weight percent is 90.0 to adhere to internationally recognised standards for platinum jewellery for example 900 Pt (90 wt% platinum).
- a minimum amount of platinum (or sum of platinum and iridium) in weight percent is 95.0 to adhere to 950 Pt (95 wt% platinum).
- Nickel, cobalt, copper, iron and manganese all lower the melting point of pure Pt and increase hardness by a combination of solid solution and precipitation strengthening. In addition, they are relatively unreactive, meaning their alloys with Pt can be repeatedly remelted without appreciably changing the composition of the alloy due to reactions with the atmosphere, crucible walls or mould walls. Cobalt, manganese and iron amounts are limited in Table 1 because case additions beyond the ranges specified in Table 1 are unlikely to bring additional benefits as they may not appreciably reduce the melting point further, may result in an excessive fraction of intermetallic phases upon cooling of the casting or may increase the solidification range.
- high cobalt can render an alloy ferromagnetic which can cause fabrication issues, iron may cause undesirable ferromagnetism and can also form an intermetallic phase at high temperatures which is suspected to harm ductility and high manganese can evaporate from melt thereby causing processing issues.
- Each of these elements may independently of one another be limited to 10.0 wt% or less.
- nickel there is a concern about its use in jewellery applications because of allergy concerns. Therefore the amount of nickel is kept at 7.0 wt% or less, preferably 5.0 wt% or less or even 4.0 wt% or less.
- nickel is particularly useful for the purposes given above for this group of elements and so nickel is preferably present in an amount of 3.0 wt% or more.
- Copper is limited to 10.0 wt% or less because it is relatively easily oxidised compared to the other elements in this group meaning that formation of slag during melting for casting is more likely. Slag formation is undesirable. Additionally, copper has been found to increase solidification range at higher concentrations, which is undesirable. Therefore, copper is preferably limited to 9.0 wt% or less, more desirably 8.0 wt% or less.
- Gold has a small effect of reducing the melting temperature of platinum alloys at low concentrations and increases hardness. But gold increases solidification range and so is limited to 10.0 wt% or lower. Preferably gold is limited to 5.0 wt% or 3.0 wt% or less due to its adverse effect on solidification range. Preferably gold is absent in the alloy as its presence can hinder recyclability due to difficulty in separating it from platinum.
- Palladium slightly increases hardness by a combination of solid solution and precipitation strengthening. Palladium has only a slightly reducing effect on the melting temperature and so must be supplemented by other alloying elements to reduce the melting point sufficiently (equation (1)). However, palladium is unreactive and so is limited in Table 1 only by the minimum required amount of platinum. Thus, in an embodiment the alloy contains palladium and at least two further alloying elements (two or more selected from tin, indium and gallium, as described below). In an embodiment, palladium is absent in the alloy as its presence can hinder recyclability due to difficulty in separating it from platinum (in which case one or more of cobalt, iron, nickel and copper is present, as described below).
- palladium is currently more than twice the cost of platinum and is therefore undesirable as it increases the cost of the alloy.
- platinumpalladium alloys are known to be poorly workable - the palladium content is therefore preferably reduced to 5.0wt% or less when good workability is to be achieved.
- the alloy is essentially palladium free (i.e. consists of 0.0 wt% or less).
- Rhodium, iridium, ruthenium and rhenium are very noble meaning their alloys with Pt can be repeatedly remelted without appreciably changing the composition of the alloy due to reactions with the atmosphere, crucible walls or mould walls. In addition, they increase hardness by solid solution strengthening. However, excessive additions of iridium and/or rhodium and/or rhenium may appreciably increase the cost of the alloy and raise its melting point which adversely affects its castability. Therefore, the amounts of rhodium, iridium and rhenium are limited to 5.0 wt% or less each, preferably 3.0 wt% or less each.
- Ruthenium may result in excessively poor castability and so is limited to 10.0 wt% or less, preferably 5.0 wt% or less or even 3.0 wt% or less.
- one or more of rhodium, iridium, rhenium and ruthenium are absent in the alloy as their presence can hinder recyclability due to difficulty in separating them from platinum.
- Tin, indium, gallium all lower the melting point of pure Pt significantly and strongly increase hardness by precipitation strengthening.
- excessive additions may result in an excessive fraction of intermetallic phases upon cooling of the casting or may excessively increase the solidification range.
- the amount of indium is limited to 3.0 wt% or less (preferably 2.0 wt% or less or even 1.0 wt% or less)
- the amount of tin is limited to 3.0 wt% or less (preferably 2.0 wt% or less or even 1.0 wt% or less).
- the amount of gallium is limited to 4.0 wt% or less (preferably 3.0 wt% or 2.0 wt% or less).
- Indium and tin have been found particularly effective and so preferably indium is present in an amount of 0.5wt% or more and/or tin is present in an amount of 0.5 wt% or more.
- the alloys in the invention may also contain small amounts of other elements, as incidental impurities. These include titanium, aluminium, chromium, zinc, yttrium, hafnium, zirconium, vanadium, niobium, tantalum, molybdenum, tungsten, silver, scandium, any lanthanide, germanium.
- Total incidental impurities make up 1.0 wt% or less of the alloy, preferably 0.5 wt% or less of the alloy. Any single impurity element is present at a level of 0.5 wt% or less, preferably 0.25 wt% or less or even 0.1 wt% or less.
- aluminium and/or chromium and/or titanium may be effectively absent.
- the second step relies upon thermodynamic calculations used to calculate the phase diagram and thermodynamic properties for a specific alloy composition. Often this is referred to as the CALPHAD method (CALculation of PHAse Diagrams).
- a third stage involves isolating alloy compositions which have the desired properties as calculated in the second step.
- the candidate alloys in the investigated composition space were selected based on the various merit indices indicative of the two targets: good castability and good mechanical properties.
- the melting point index reflects the melting point of the alloy which is derivable directly from the thermodynamic calculations. A lower value is better as a low melting point means metal-mould reactions can be suppressed, thereby lowering gas porosity and improving the surface finish. A lower melting point also allows for a higher superheat relative to one with a higher melting point. A higher superheat increases fluidity and improves the form filling characteristics of the alloy.
- the (equilibrium) solidification range the range of in which the alloy would solidify if perfect thermodynamic equilibrium were maintained throughout. That is, assuming thermodynamic equilibrium, the temperature where on heating liquid first appears subtracted from the temperature on heating at which the last solid melts. This is directly derivable from the thermodynamic calculations.
- a larger range is generally associated with excessive elemental segregation in the as- cast microstructure which results in poor mechanical properties of the casting and in increased risk of hot cracking - i.e. crack formation in the casting during solidification.
- the hot cracking index this index more accurately reflects the risk of hot cracking than the solidification range as the underlying Scheil model takes into account the segregation during nonequilibrium solidification conditions encountered in the vast majority of industrial settings.
- the Scheil model assumes that as the melt solidifies, the diffusion in it is infinitely fast and there is no back-diffusion from the already solidified material.
- the remaining liquid phase e.g. Ga, Cu
- the liquid phase e.g. Ga, Cu
- the hot cracking index itself is based on the ratio of the temperature drop required for the last stage of solidification (typically 90% to 99%) and the initial stage of the solidification - from 40% to 90% solid.
- the porosity index the relative change in molar volume of an alloy between the beginning and the end of Scheil solidification (i.e. the shrinkage in initial stage of solidification). Larger thermal strains are more difficult to accommodate, particularly towards the end of the solidification. If such strains are excessive, the alloy is at risk of shrinkage porosity which is undesirable in castings.
- the hardness index gives the hardness of the as-cast alloy based on its elemental composition. This index is based on a statistical analysis of experimental hardness data of a wide range of platinum alloys available in the literature (Equation (2)). A higher value is generally better, although hardness values beyond 220 HV may adversely affect gem setting and so may not be desirable for certain applications.
- the alloys in this invention may form large volume fractions of brittle intermetallic phases even at high temperatures at the expense of the ductile platinum gamma matrix phase (a disordered FCC solid solution phase). Intermetallic phases are desirable for improving hardness but an excessively high volume fraction decreases ductility below an acceptable level.
- the gamma fraction merit index is preferably set such that the volume fraction of the platinum gamma matrix phase is at least 0.3 at thermodynamic equilibrium at 1000 °C.
- Table 3 shows that all benchmark alloys except Ptl.5ln3Ga and Pt5N i have a melting point index above 16.6 indicating a high melting point.
- High melt temperatures during casting are known to exacerbate metal-mould reactions, leading to increased shrinkage and gas porosity, increased risk of inclusions and investment cracking and contamination with alloy-mould reaction products.
- An alloy with a lower melting point also allows for a higher superheat relative to one with a higher melting point. A higher superheat increases fluidity and improves the form filling characteristics of the alloy.
- a platinum alloy with a low melting point is therefore desirable from the point of view of castability.
- Ptl.5ln3.0Ga has a large solidification range (due to the high level of gallium) as well as a gamma phase fraction of below 1.0, meaning that the possibility of intermetallic phase precipitation is increased.
- Figure 1 plots for thousands of alloy compositions falling throughout the range allowed by Table 1 both the melting point index (x-axis) and the hardness merit index (y-axis). Also plotted on the graph are the alloys with composition of Table 2 in their relative positions. As can be seen, alloys with a melting point index less than 16 (and thereby with superior castability than for those alloys with a melting point index of greater than 16) also tend to have a hardness greater than that of the majority of the prior art alloys.
- Figure 1 shows that many Pt alloys with a composition according to Table 1 have a melting point comparable to or lower than all the benchmark alloys, including Ptl.5ln3Ga. Figure 1 also shows that many Pt alloys meeting the Table 1 composition have a hardness higher than all the benchmark alloys.
- Figure 2 is a comparison of gamma phase (FCC platinum solid solution) volume fraction and melting point index between the example alloys and benchmarks. It shows that many alloys with gamma phase volume fractions as low as 0.3 (and so acceptable ductility) achieve the required melting point index of 16.6.
- Figure 3 shows that for many alloys which achieve a melting point index of lower than 16.6, a hot cracking index of 4.0 or lower is achievable. This area is shown by the cross hatched polygon.
- Figure 4 shows that for alloys with a melting point index of less than 16.6, there are several alloys which also achieve a solidification range of 200 °C or less. The preferred solidification range of less than 150 °C is shown in cross hatch. Alloys with a solidification range of greater than 150 °C have been omitted from this graph.
- the alloy selection procedure was based on several guidelines: first, the main metric for improved castability is a low melting point index. A melting point index of below 16.0 results in an alloy with a significantly lower melting point than any of the prior art alloys in Table 3. Such a low melting point index is harder to achieve for the high platinum containing alloys and for such alloys (i.e. with a Pt content of 95.0 wt% or more), the melting point index requirement is relaxed to 16.6 or less. This is acceptable because for high value jewellery (i.e. high Pt content), some machining (e.g. polishing) after casting is acceptable and there may be more limitations on the alloying elements which can be used considering potential requirements for high hardness and low solidification range. Second, for improved mechanical properties, hardness values should exceed 150 HV but should be tuneable as hardness requirements may vary depending on the application.
- W Co , W Cu , W Fe , W Ga , W In , W Ni , W Pd , W Sn , W Mn , W Ru , W Ir , W Rh , W Au and W Re are the weight percent of cobalt, copper, iron, gallium, indium, nickel, palladium, tin, manganese, ruthenium, iridium, rhodium, gold and rhenium in the alloy respectively.
- Alloy compositions exist within the range of Table 1 with an even higher melting point index.
- equation (1) is 16.0 or less.
- Alloys with lower values of equation (1) are preferred, particularly those in which equation (1) is 15.5 or less, more preferably 15.0 or less and most preferably 14.5 or less.
- W Co , W Cu , W Fe , W Ga , W In , W Ni , W Pd , W sn , W Rh , W ir , W Au , W Ru , W Re , and W Mn are the weight percent of cobalt, copper, iron, gallium, indium, nickel, palladium, tin, rhodium, iridium, gold, ruthenium, rhenium, and manganese in the alloy respectively.
- equation (2) is greater than or equal to 150 (as is achievable by alloys of the present invention as shown in Table 5 below), the hardness of the platinum alloy will be acceptable.
- equation (2) is greater than or equal to 200, preferably 225, more preferably 250, even more preferably 275 or most preferably 300, in which case an alloy with a correspondingly increased hardness results and this may be preferred for certain applications.
- Those skilled in the art of jewellery know hardness should be high enough to improve wear resistance, and facilitate gem setting as well as polishing, but if hardness is too high, softer gemstones risk getting damaged during setting.
- the composition space allows a wide hardness range and alloys in the invention have a hardness of at least 150 HV.
- equation (2) is less than or equal to 280, more preferably less than or equal to 260, and most preferably less than or equal to 240.
- Solidification range excessive range often results in solidification defects.
- the alloy preferably has a solidification range of less than 200 °C, preferably the alloy composition has a solidification range of 150 °C or less. More preferably wherein the alloy composition has a solidification range of 125°C or less, more preferably wherein the alloy composition has a solidification range of 100 °C or less, even more preferably wherein the alloy composition has a solidification range of 75 °C or less, most preferably wherein the alloy composition has a solidification range of 50 °C or less.
- the inventors have found ensuring that the following equation is satisfied: 0.35W Au + 0.6W sn + 0.6W In + W Ga ⁇ 3.75 helps to produce an alloy with a lower solidification range.
- Equation (4) must be fulfilled so that the desired melting point can be achieved without increasing the solidification range excessively.
- the complicated interaction between elements means that it has not been possible for the inventors to derive an accurate equation using simple ratios of all the elements in Table 1 defining the solidification range from the thermodynamic data.
- solidification range can be measured experimentally by differential scanning calorimetry. The difference (in Kelvin) between the onset and end of the exothermic peak associated with the phase transition from liquid to solid upon slow cooling (at the rate of 10 K/min or less) is defined as the solidification range.
- the alloy consists, in weight percent, of: 0.0 to 5.0 cobalt, 0.0 to 10.0 copper, 0.0 to 7.0 iron, 0.0 to 4.0 gallium, 0.0 to 3.0 indium, 0.0 to 7.0 nickel, 0.0 to 15.0 palladium, 0.0 to 3.0 tin, 85.0 or more platinum and incidental impurities.
- Such alloys are preferred because gold and manganese have low effect on melting point and hardness, but increase the solidification range and iridium, rhenium, rhodium and ruthenium tend to increase the melting point.
- the value of equation (3) is equal to or less than 140.
- Such an alloy has improved castability due to lower solidification range.
- the value of equation (3) is equal to or less than 120 or even equal to or less than 100, or even equal to or less than 80 and most preferably equal to or less than 60.
- the alloys in the invention are characterised by a combination of sufficient hardness as well as a narrow solidification range and a low melting point, whose combination leads to good castability . Two distinct groups of alloying elements can be identified: those which improve castability by lowering the melting point and not excessively increasing the solidification range (Ni, Co, Fe, Pd and Cu) and those which increase hardness and decrease the melting point but decrease castability by increasing the solidification range (Sn, In, Ga).
- the alloys in the invention need at least one of the elements from each group in order to satisfy both criteria according to equations
- W Co + W Pd + W Fe + W Ni + W Cu ⁇ 2.0 as such an alloy has lower melting point without a large increase in solidification range.
- the lowest fraction of terminal intermetallics is achieved when all three elements are present. While it is true that using pure Sn or In yields less terminal intermetallics than using a combination of three elements when the fraction of Ga exceeds about 0.4, a high Ga content may be desirable for other reasons - for example to achieve a very high hardness. In this case, replacing some Ga with In or Sn will only somewhat reduce hardness but could appreciably reduce the fraction of terminal intermetallics. While one can use a combination of Ga and In or Ga and Sn to achieve a desired hardness, using all three elements will, at the same time, reduce the fraction of terminal intermetallics may therefore be preferable.
- alloys with indium and tin, of the group of gallium, indium and tin, two of which are compulsory, have lower levels of terminal intermetallics than alloys without those two elements. Therefore preferably indium and tin are the two elements of gallium, indium and tin which are present, where reduced intermetallic precipitation is preferred over other properties.
- the amount of intermetallic can be reduced compared to the case where only small amounts of the second or third of those three elements are present.
- the two or more of gallium, indium and tin are indium and gallium, preferably the following equation is satisfied in which W Ga and W In , , are the weight percent of gallium and indium in the alloy
- indium and tin are indium and tin preferably the following equation is satisfied in which W In , and W Sn , are the weight percent of indium and tin in the alloy
- the two or more of gallium, indium and tin are indium, tin and gallium preferably the following equations are satisfied in which W Ga , W In , and W sn , are the weight percent of gallium, indium and tin in the alloy
- Hot cracking excessive values often result in solidification defects, particularly cracking.
- the PtlOAu benchmark alloy has the largest index value yet it is not excessively prone to cracking during solidification. Hot cracking index was therefore limited to somewhat less than the hot cracking value of Pt10Au.
- the following equation (6) was derived which expresses the hot cracking index as a function of composition. The equation is derived from results of alloys falling within the range of Table 1. Therefore, for a platinum alloy falling within the compositional range of Table 1 and in which equation (6) below is 4.0 or less, such an alloy will have superior castability compared to PtlOAu.
- the hot cracking index of equation 3 is 3.941 or less. All examples of the invention in Table 4 fall within that range.
- W Co , W Cu , W Fe , W Ga , W In , W Ni , W Pd , W sn , W Mn and W Au are the weight percent of cobalt, copper, iron, gallium, indium, nickel, palladium, tin, manganese and gold in the alloy respectively.
- the hot cracking index is 3.5 or less, or even 3.0 or less, or even 2.5 or less.
- equation (6) is preferably 3.5 or less, or even 3.0 or less or most preferably 2.5 or less.
- the minimum equilibrium volume fraction of the ductile gamma matrix phase at 1000 °C is desirably 0.3, which is achieved by many of the examples.
- the alloy composition comprises 0.55 or more volume fraction gamma phase at 1000 °C, preferably 0.6 or more volume fraction gamma phase, more preferably 0.7 or more volume fraction gamma phase, even more preferably 0.8 or more volume fraction gamma phase, most preferably 0.9 or more volume fraction gamma phase.
- results of thermodynamic calculations have not allowed a simple equation to be derived which predicts the volume fraction gamma prime based on the composition.
- composition can be determined experimentally by the following method. After a substantially long thermal exposure (for example 200 h) at 1000 °C the specimen is quenched in water, a section is taken through the material and polished using conventional/standard metallurgical preparation techniques for scanning electron microscopy.
- the microstructure should be observed in a scanning electron microscope. A minimum of 10 images should be taken which provide a statistically representative dataset. The images should cover an area of at least 1 mm 2 .
- the measured area fractions correspond directly to volume fractions.
- the alloys preferably are those which first form gamma phase on cooling from liquid. In the gamma phase all alloying elements are in solid solution. This can be determined experimentally by following the procedure similar to the one in the paragraph above. The procedure is modified by instead measuring the area fraction of any simple polygonal precipitates whose orientation is random and whose largest diameter exceeds 0.2 mm. If their area fraction exceeds 0.025, this is indicative of excessive intermetallic precipitation directly from the melt.
- condition 2.5Wi r + 3W Ru ⁇ 7.5 is preferably met in order to achieve a low melting point.
- the alloy consists of platinum, cobalt, iron, nickel and palladium, with any other elements being present in a sum amount of 1.0 wt% or less (preferably 0.5 wt% or less) and any individual other element present in an amount of 0.5 wt% or less (preferably 0.25 wt% or less). This is advantageous because Fe and Ni lower the melting point more effectively than Co and Pd so more of the latter is needed to achieve the same effect.
- the platinum alloy composition is made up of 95 weight percent or more of platinum and satisfies the following equation in which W Co , W Fe , and W Ni , are the weight percent of cobalt, iron, and nickel in the alloy 3.0 ⁇ W Co + W Fe + W Ni ⁇ 4.5 as well as the following equation in which W Ga , W In , and W sn , are the weight percent of gallium, indium and tin in the alloy 0.4 ⁇ W Ga + W In + W sn ⁇ 2.2.
- W Co , W Fe , and W Ni are the weight percent of cobalt, iron, and nickel in the alloy 3.0 ⁇ W Co + W Fe + W Ni ⁇ 4.5 as well as the following equation in which W Ga , W In , and W sn , are the weight percent of gallium, indium and tin in the alloy 0.4 ⁇ W Ga + W In + W sn ⁇ 2.2.
- Such an alloy has a good balance of castability and hardness while still meeting the 950 platinum hallmark
- Table 4 gives several example alloy compositions which fall within the present invention. That is, all alloy compositions fall within the range of compositions of Table 1. All values are in weight percent.
- Table 5 shows the main properties achieved by these examples, namely gamma fraction as predicted by the thermodynamic model, hardness as predicted by the above-mentioned equation, hot cracking index as indicated by the abovementioned fit, melting point index as obtained by the above- mentioned fit, and solidification range as measured by the thermodynamic model.
- the hot cracking index of the range of alloys compares favourably to the hot cracking index of many of the prior art alloys.
- the examples of the present invention achieve the desired low melting point and high hardness by incorporating two or more, preferably three or more of the gallium, indium and tin and one or more of cobalt, palladium, iron, nickel and copper.
- Comparative example 2 shows good form filling but has extensive shrinkage porosity (due to too large a solidification range) and may be considered too hard for many jewellery applications.
- Example 0 from this invention performs well on both castability metrics and is neither too hard nor too soft.
- Example 0 Machinability trials on showed that examples from this invention (Example 0) have superior machinability compared to the commonly used Comparative example 2.
- a CNC rig using tungsten carbide tooling was used to machine a groove for gem setting in a simple ring. The comparison is shown in Figure 8 - the machined groove in a band made of Comparative example 2 is full of burrs. Their presence is undesirable as removing them is a time-consuming process.
- Example 0 shows clean edges. Unlike in Comparative example 2 small steps were observed in the groove formed by subsequent tool passes. This indicates Example 0 is suitable for precision machining.
- Example 0 and Comparative example 2 were tested, both vacuum investment cast into flasks of essentially the same design. In both cases, the melt was heated to approximately 200 °C above the melting point before casting while the flask temperature was 732 °C. While the most complex ring design (furthest back) was not fully filled by either alloy, Example 0 came much closer to complete fill. Example 0 also fully filled the ring at the front of the casting tree while the same design in Comparative example 2 (right-hand side of the casting tree) is showed only a partial fill.
- the alloy of example 0 is particularly promising and has excellent properties.
- a particularly preferred alloy consists, in weight percent, of 0.0 to 2.0 indium, 0.0 to 5.0 nickel and 0.0 to 2.0 tin, with the balance being platinum and incidental impurities, preferably 0.5 to 1.0 indium, 3.0 to 4.0 nickel and 0.5 to 1.0 tin.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Catalysts (AREA)
- Adornments (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
Abstract
Description
Claims
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP21794611.0A EP4225957A1 (en) | 2020-10-05 | 2021-10-01 | A platinum alloy composition |
CA3196408A CA3196408A1 (en) | 2020-10-05 | 2021-10-01 | A platinum alloy composition |
CN202180067816.4A CN116437833A (en) | 2020-10-05 | 2021-10-01 | Platinum alloy composition |
AU2021356222A AU2021356222A1 (en) | 2020-10-05 | 2021-10-01 | A platinum alloy composition |
JP2023521025A JP2023543633A (en) | 2020-10-05 | 2021-10-01 | platinum alloy composition |
KR1020237015049A KR20230104613A (en) | 2020-10-05 | 2021-10-01 | platinum alloy composition |
US18/028,820 US20230366064A1 (en) | 2020-10-05 | 2021-10-01 | A platinum alloy composition |
ZA2023/03454A ZA202303454B (en) | 2020-10-05 | 2023-03-09 | A platinum alloy composition |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2015742.6 | 2020-10-05 | ||
GBGB2015742.6A GB202015742D0 (en) | 2020-10-05 | 2020-10-05 | A platinum alloy composition |
GB2103613.2 | 2021-03-16 | ||
GB2103613.2A GB2599462B (en) | 2020-10-05 | 2021-03-16 | A platinum alloy composition |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2022074363A1 true WO2022074363A1 (en) | 2022-04-14 |
Family
ID=73223771
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2021/052542 WO2022074363A1 (en) | 2020-10-05 | 2021-10-01 | A platinum alloy composition |
Country Status (10)
Country | Link |
---|---|
US (1) | US20230366064A1 (en) |
EP (1) | EP4225957A1 (en) |
JP (1) | JP2023543633A (en) |
KR (1) | KR20230104613A (en) |
CN (1) | CN116437833A (en) |
AU (1) | AU2021356222A1 (en) |
CA (1) | CA3196408A1 (en) |
GB (2) | GB202015742D0 (en) |
WO (1) | WO2022074363A1 (en) |
ZA (1) | ZA202303454B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN115896529A (en) * | 2022-11-09 | 2023-04-04 | 有研亿金新材料有限公司 | Platinum alloy for ornaments and preparation method thereof |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4165983A (en) * | 1977-02-23 | 1979-08-28 | Johnson, Matthey & Co., Limited | Jewelry alloys |
JPS6134137A (en) * | 1984-07-25 | 1986-02-18 | Tanaka Kikinzoku Kogyo Kk | Platinum alloy for accessory |
ITMI20110750A1 (en) * | 2011-05-04 | 2012-11-05 | Legor Group S P A | PLATINUM-COBALT ALLOYS WITH IMPROVED HARDNESS |
DE102014224687A1 (en) * | 2014-12-03 | 2016-06-09 | Robert Bosch Gmbh | Metal layer and process and coating liquid for its production |
EP3121297A1 (en) * | 2015-07-23 | 2017-01-25 | Cartier International AG | Method for obtaining a trim component in platinum alloy |
JP2018021239A (en) * | 2016-08-04 | 2018-02-08 | マオン株式会社 | Platinum alloy for ornament |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5716140A (en) * | 1980-07-03 | 1982-01-27 | Tanaka Kikinzoku Kogyo Kk | Platinum alloy for decoration |
JPS5743945A (en) * | 1980-08-29 | 1982-03-12 | Tanaka Kikinzoku Kogyo Kk | Platinum alloy for ornamental product |
JPS5743946A (en) * | 1980-08-29 | 1982-03-12 | Tanaka Kikinzoku Kogyo Kk | Platinum alloy for ornamental product |
-
2020
- 2020-10-05 GB GBGB2015742.6A patent/GB202015742D0/en not_active Ceased
-
2021
- 2021-03-16 GB GB2103613.2A patent/GB2599462B/en active Active
- 2021-10-01 US US18/028,820 patent/US20230366064A1/en active Pending
- 2021-10-01 CA CA3196408A patent/CA3196408A1/en active Pending
- 2021-10-01 KR KR1020237015049A patent/KR20230104613A/en unknown
- 2021-10-01 JP JP2023521025A patent/JP2023543633A/en active Pending
- 2021-10-01 CN CN202180067816.4A patent/CN116437833A/en active Pending
- 2021-10-01 EP EP21794611.0A patent/EP4225957A1/en active Pending
- 2021-10-01 AU AU2021356222A patent/AU2021356222A1/en active Pending
- 2021-10-01 WO PCT/GB2021/052542 patent/WO2022074363A1/en unknown
-
2023
- 2023-03-09 ZA ZA2023/03454A patent/ZA202303454B/en unknown
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4165983A (en) * | 1977-02-23 | 1979-08-28 | Johnson, Matthey & Co., Limited | Jewelry alloys |
JPS6134137A (en) * | 1984-07-25 | 1986-02-18 | Tanaka Kikinzoku Kogyo Kk | Platinum alloy for accessory |
ITMI20110750A1 (en) * | 2011-05-04 | 2012-11-05 | Legor Group S P A | PLATINUM-COBALT ALLOYS WITH IMPROVED HARDNESS |
DE102014224687A1 (en) * | 2014-12-03 | 2016-06-09 | Robert Bosch Gmbh | Metal layer and process and coating liquid for its production |
EP3121297A1 (en) * | 2015-07-23 | 2017-01-25 | Cartier International AG | Method for obtaining a trim component in platinum alloy |
JP2018021239A (en) * | 2016-08-04 | 2018-02-08 | マオン株式会社 | Platinum alloy for ornament |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN115896529A (en) * | 2022-11-09 | 2023-04-04 | 有研亿金新材料有限公司 | Platinum alloy for ornaments and preparation method thereof |
Also Published As
Publication number | Publication date |
---|---|
US20230366064A1 (en) | 2023-11-16 |
CN116437833A (en) | 2023-07-14 |
GB202103613D0 (en) | 2021-04-28 |
CA3196408A1 (en) | 2022-04-14 |
GB2599462A (en) | 2022-04-06 |
GB202015742D0 (en) | 2020-11-18 |
KR20230104613A (en) | 2023-07-10 |
GB2599462B (en) | 2023-06-14 |
ZA202303454B (en) | 2024-04-24 |
EP4225957A1 (en) | 2023-08-16 |
JP2023543633A (en) | 2023-10-17 |
AU2021356222A1 (en) | 2023-05-25 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3356542A (en) | Cobalt-nickel base alloys containing chromium and molybdenum | |
EP1897962B1 (en) | Creep resistant magnesium alloy with improved ductility and fracture toughness for gravity casting applications | |
JP5709402B2 (en) | Cobalt-nickel superalloy and related articles | |
CA2238070C (en) | Magnesium alloy having superior elevated-temperature properties and die castability | |
CA2737329A1 (en) | Cobalt-nickel superalloys, and related articles | |
JP2008542534A (en) | Aluminum casting alloy, aluminum alloy casting, and manufacturing method of aluminum alloy casting | |
JP4424503B2 (en) | Steel bar and wire rod | |
KR102623143B1 (en) | Free-cutting copper alloy castings, and method for manufacturing free-cutting copper alloy castings | |
RU2695852C2 (en) | α-β TITANIUM ALLOY | |
JP2008542533A (en) | Aluminum casting alloy and method for producing the same | |
JP2001220639A (en) | Aluminum alloy for casting | |
JP2016539248A (en) | Antibacterial white copper alloy | |
US20230366064A1 (en) | A platinum alloy composition | |
JP5010841B2 (en) | Ni3Si-Ni3Ti-Ni3Nb multiphase intermetallic compound, method for producing the same, high-temperature structural material | |
US20210246531A1 (en) | Copper-based casting products and processes | |
KR20220129568A (en) | Die-cast aluminum alloy for structural elements | |
JP2004524974A (en) | High-temperature isostatic compression molding of castings | |
JP7129057B2 (en) | Method for producing Ti-based alloy | |
JP6660042B2 (en) | Method for manufacturing extruded Ni-base superalloy and extruded Ni-base superalloy | |
US20160102392A1 (en) | Methods of making and treating copper-based alloy compositions and products formed therefrom | |
Iecks et al. | Designing a microstructural array associated with hardness of dual-phase Cu-Zn alloy using investment casting | |
CN108884517A (en) | The manufacturing method of titanium alloy, clock exterior member material | |
Donahue et al. | New Hypoeutectic/Hypereutectic Die-Casting Alloys and New Permanent Mould Casting Alloys That Rely on Strontium for Their Die Soldering Resistance | |
JP2015187304A (en) | Heat resistant alloy excellent in high temperature strength, method for producing the same, and heat resistant alloy spring | |
JP6699989B2 (en) | Articles and method of manufacturing articles |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 21794611 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 3196408 Country of ref document: CA |
|
ENP | Entry into the national phase |
Ref document number: 2023521025 Country of ref document: JP Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 2021794611 Country of ref document: EP Effective date: 20230508 |
|
ENP | Entry into the national phase |
Ref document number: 2021356222 Country of ref document: AU Date of ref document: 20211001 Kind code of ref document: A |