CA1064734A - High strength low density amorphous beryllium metal alloy - Google Patents
High strength low density amorphous beryllium metal alloyInfo
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Abstract
INVENTION: ZIRCONIUM-CONTAINING AMORPHOUS
METAL ALLOYS
INVENTORS: LEE E. TANNER
RANJAN RAY
CARL F. CLINE
ABSTRACT OF THE INVENTION
Amorphous metal alloys are prepared from compositions in the beryllium-titanium-zirconium system. The compositions are defined as those of the formula BeaTibZrcXd, wherein X is at least one additional alloying element selected from the group consisting of the transition metals listed in Groups IB
to VIIB and Group VIII, Rows 4, 5 and 6, of the Periodic Table and of the metalloid elements phosphorus, boron, carbon, aluminum, silicon, tin, germanium, indium and antimony; "a" varies from 30 to 52 atom percent, "b" from 0 to 68 atom percent, "c"
varies from 0 to 70 atom percent, and "d" varies from 0 to 10 atom percent. These alloys evidence high strength, low density and good ductility. The alloys are useful in applications requiring a high strength-to-weight ratio.
METAL ALLOYS
INVENTORS: LEE E. TANNER
RANJAN RAY
CARL F. CLINE
ABSTRACT OF THE INVENTION
Amorphous metal alloys are prepared from compositions in the beryllium-titanium-zirconium system. The compositions are defined as those of the formula BeaTibZrcXd, wherein X is at least one additional alloying element selected from the group consisting of the transition metals listed in Groups IB
to VIIB and Group VIII, Rows 4, 5 and 6, of the Periodic Table and of the metalloid elements phosphorus, boron, carbon, aluminum, silicon, tin, germanium, indium and antimony; "a" varies from 30 to 52 atom percent, "b" from 0 to 68 atom percent, "c"
varies from 0 to 70 atom percent, and "d" varies from 0 to 10 atom percent. These alloys evidence high strength, low density and good ductility. The alloys are useful in applications requiring a high strength-to-weight ratio.
Description
6D~734 ZIRCONIUM-CONT~INING AMORPHOUS
METAL ALLOYS
.
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to amorphous metal alloys, and, more particularly, to high strength, low density compositions in the beryllium~titanium-zirconium system.
METAL ALLOYS
.
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to amorphous metal alloys, and, more particularly, to high strength, low density compositions in the beryllium~titanium-zirconium system.
2~ Description of the Prior Art Investigations have demonstrated that it is possible to obtain solid amorphous materials from certain metal alloy compositions. An amorphous material substantially lacks any long range order and is characterized by an X-ray di~fraction profile in which intensity varies slowly with diffraction angle. Such a profile is ~ualitatively similar to the diffraction profile of a liquid or ordinary window glass. This is in contrast to a crystalline material which produces a diffraction profile in which intensity varies rapidly with diffraction angle.
These amorphous metals exist in a metastable state.
Upon heating to a sufficiently high temperature, they crystallize with evolution of heat of crystallization, and the X-ray diffraction profile changes from one having amorphous charac-`I 20 teristics to one having crystalline characteristics.
Z Novel amorphous metal alloys have been disclosed and claimed by H. S. Chen and D. E. Pol~ in U.S. Patent 3,856,513, issued December 24, 1974. These amorphous alloys have the formula MaYbZC where M is at least one metal selected from the group of iron, nickel, cobalt, chromium and vanadium, Y
is at least on~ element selected from the group consisting of phosphorus, boron and carbon, Z is at least one element selected from the group consisting of aluminum, antimony, beryllium, germanium, indium, tin and silicon, "a" ranges from about 60 to 90 atom percent, "b" ranges ~rom about 10 to 30 atom percent ~' ~
, 73~
and "c" ranges from about 0.1 to 15 atom percent. Theseamorphous alloys have been found suitable for a wide variety of applications, including ribbon, sheet, wire, powder, etc.
Amorphous alloys are also disclosed and claimed having the formula TiXj, where T is at least one transition metal, X is at least one element sele~ted from the group consisting of aluminum, antimony, beryllium, boron, germanium, carbon, indium, phosphorus, silicon and tin, "i" ranges from about 70 to 87 atom percent and "j" ranges from about 13 to 30 atom percent. These amorphous alloys have been found suitable for wire applications.
At the time these amorphous alloys were discovered, they evidenced mechanical properties that were superior to then known polycrystalline alloys. Such superior mechanical pro-perties included ultimate tensile strengths of up to 350,000 psi, hardness values (DPH) of about 650 to 750 kg/mm2 and good ductility. Nevertheless, new applications requiring improved magnetic, physical and mechanical properties and higher thermal stability have necessitated efforts to develop further compositions. More specifically, there remains a need for high strength, low density material suitable for structural applications.
SUMM~RY OF THE INVENTION
In accordance with the invention, high strength, low density amorphous metal alloys are formed from compositions of the formula BeaTibZrcXd, wherein X is at least one additional alloying element selected from the group consisting of the transition metals listed in Groups IB to VIIB and Group VII~, Rows 4, 5 and 6, of the Periodic Table and of the metalloid elements phosphorus, boron, carbon, aluminum, silicon, tin, germanium, indium and antimony; "a"
varies from 30 to 52 atom percent, "b" from 0 to 68 atom percent ~2--lQ~734 "c" varies from 0 to 70 atom percent, and "d" varies from 0 to lO
atom percent. Two species of alloy within this formula are (I) those formed from compositions having about 48 to 68 atom percent titanium, about 32 to 52 atom percent beryllium, with a maximum of up to about 10 atom percent of beryllium replaced by at least one additional alloying element, selected from the group consisting of transition metals listed in Groups IB to VIIB and Group VIII, Rows 4, 5 and 6 of the Periodic Table, and metalloid elements phosphorus, boron, carbon, aluminum, silicon, tin, germanium, indium and antimony. Preferably, amorphous titanium-beryllium base alloys are formed from compo-sitions having about 50 to 61 atom percent titanium, about 37 to 41 atom percent beryllium and about 2 to 10 atom percent of at least one element selected from the group consisting of aluminum, boron, tantalum and zirconium. Also, preferred are amorphous titanium-beryllium binary alloys formed from ; ` compositions having from about 58 to 68 atom pe~cent titanium and from about 32 to 42 atom percent beryllium. The second species (II) of compositions according to the invention are those defined within an area on a ternary diagram, having as its coordinates in atom percent Be, atom percent Ti and atom percent Zr, the area being defined by a polygon having at its corners the five points defined by ; (a) 30% Be, 0% Ti, 70% Zr tb) 50% Be, 0% Ti, 50% Zr (c) 50% Be, 40% Ti, lO~ Zr (d) 42% Be, 56% Ti, 2% zr (e) 36~ Be, 62% Ti, 2% Zr.
The alloys of the invention evidence specific strengths of about 28 to 60 x 105 cm. Also, the alloys of this invention 73~
are at least 50% amorphous, and preferably substantially amorphous, that is, at least 80~ amorphous; and most preferably about 100% amorphous~ as determined by X-ray diffraction.
The amorphous metal alloys are fabricated by a process which comprises forming a melt of the desired composition and quenching at a rate of about 105 to 106C./sec by castlng molten alloy onto a chill wheel in an inert atmosphere or in a partial vacuum.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a ternary phase diagr.am, in atom percent, : of the Ti~Be-X, system of species (I) where X represents at least one additional alloying element, depicting the glass-forming range;
` ~IG. 2 is a binary phase diagram, in atom p~rcent, - --of the Ti-Be system within species (I) depicting the glass-forming range.
FIG. 3 is a ternary phase diagram in atom percent of the Be-Ti-Zr system within species (II) depicting the glass-forming region.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the invention, high strength, low density amorphous metal alloys are formed from compositions ; of the formula BeaTibzrcxd~ wherein X is at least one additional alloying element selected from the group consisting of the transition metals listed in Groups IB to VIIB and Group VIII, Rows 4, 5 and 6, of the Periodic Table and of the metalloid elements phosphorus boron, carbon, alluminum, silicon, tin, germanium, indium and antimony; "a" varies from 30 to 52 atom 30 percent, "b" from 0 to 68 atom percent, "c" varies from 0 to 70 atom percent, and "d" varies from 0 to 10 atom percent.
~473~
The amorphous metal alloys in accordance with theinvention comprise about 30 to 52 atom percent beryllium, zero to about 68 atom percent titanium and zero to about 70 atom percent zirconium, with a maximum of up to about 10 atom percent of one additional alloying element selected from the group consisting of transition metal elements and metalloids. The transition metal elements are those listed in Groups IB to VIIB and Group ~III, Rows 4, 5 and 6 of the Periodic Table. The metalloid elements include phosphorus, boron, caebon, aluminum, silicon, tin, germanium, indium and antimony. Examples of preferred additional alloying elements include boron, aluminum, tantalum and zirconium. In a preferred species, the amorphous metal alloys have a composition consisting essentially of about 50 to 61 atom percent titanium, 37 to 41 atom percent beryllium and about 2 to 10 atom percent of at least one element selected from the group consisting of aluminum, boron, tantalum and zirconium. The purity of all elements is that found in normal commercial practice.
FIG. 1, which is a ternary composition phase diagram, depicts the glass-forming region in accordance with this species.
This region, which is designated by the polygon a-b-c-d-a, en~
compasses glass-forming compositions having high strength, good ductility and low density.
Specifically the amorphous metal alloys of the first species have a binary composition consisting essentially of about 58 to 68 atom percent titanium and about 32 to 42 atom percent beryllium. Such preferred alloys evidence high strength and low density, resulting in a high strength-to-weight ratio.
In FIGS. l and 2, the preferred range is depicted by the line a-e. As a consequence of the high strength-to-weight ratio realized for the binary system, it is preferred that any additional alloying elemen~s added have a relatively low density in order 10~73~
to retain the favorable strength-to-weight ratio. A second species (II) of alloys contemplated by the formula are defined within an area on a ternary diagram having as its coordinates in atom percent Be, atom percent Ti and atom percent Zr, the area being defined by a polygon having at its corners the five points defined by (a) 30% Be, 0% Ti, 70% Zr (b) 50% Be, 0% Ti, 50% Zr (c) 50% Be, 40% Ti, 10% Zr (d) 42% Be, 56~ Ti, 2% Zr (e) 36% Be, 62~ Ti, 2% Zr.
FIG. 3, which is ternary composition phase diagram, depicts the glass-forming region of species (II~ of the inventionO
This region, which is designated by the polygon a-b-c-d-e-a, encompasses glass-forming compositions having high strength, low density and good ductility.
Amorphous metal alloys evidencing substantial improve-ments in strength-to-weight ratios are represented by the formula Be40Ti60 xZrx, where "x" ranges from about 2 to 60 atom percent.
These alloys are depicted in the Figure by the line f-g and are preferred.
For low values of "x", that is, from about 2 to about 10 atom percent, hardness values of about 630 to 720 kg/mm2 and densities of about 3.8 to 4.1 g/cm3 are realized. While the hardness values are within the range of those of prior art amorphous alloys, the densities are considerably lower, by a factor of about 2. Since hardness is related to strength, it is evident that for low values of "x", a substantial improvement in the strength-to-weight ratio is realized. Accordingly, such compositions are especially preferred.
For higher values of "x", the hardness remains substan-tially unchanged, while the density increases to about 5.4 g/cm3, ~Gi473~
still well below that of prior art amorphous alloys. Thus, high strength to-weight ratios are retained for the entire range of compositions.
The specific strength of amorphous metal alloys is cal-culated by dividiny the hardness value (in kg/mm2) by both a dimensionless factor of about 3.~ and the density (in g/cm3).
The basis for the dimensionless factor is given in Scripta Metallurgica, Vol. 9, pp. 431-436 (1975). The high strength-to-weight properties of alloys in accordance with the invention may then be compared with those of other prior art amorphous metal alloys. For example, Pd80Si20 has a specific strength (in units of 105 cm) of 1501 and Ti50Cu50 has a specific strength of 29.6. In contrast, one of the typical preferred alloys of this invention, Be40Ti50Zr10, has a speci~ic strength of 54.8, considerably higher than that of prior art amorphous metal alloys.
In general, the amorphous metal alloys of the invention evidence specific strengths of about 28 to 60 x 105 cm.
Illustration of alloys of the invention evidencing high specific strengths are those represented by the formula given above, Be40Ti60 xZrx. Alloys within the scope of the invention evidencing lower density and the same or higher hardness values have correspondingly higher specific strengths.
Typical amorphous metal alloys of the invention evidencing good strength-to-weight ratios and exceptional ease of glass-forming behavior are represented by the formula BeyZr10O y, where "y" ranges from about 30 to 50 atom percent.
These compositions are depicted in FIG. 3 by the line a-b and are also preferred.
The amorphous metal alloys are formed by cooling a melt of the desired composition at a rate of about 105 /
~L~G~734 to 106C./sec. The purity of all compositions is that found in normal commercial practice. A variety of techniques are available, as is now well-known in the art, for fabricating splat-quenched foils and rapid-quenched continuous ribbon, wire, sheet, powder, etc. Typically, a particular composition is selected, powders or granules of the requisite elements in the desired portions are melted and homogenized, and the molten alloy i5 rapidly quenched on a chill surface, such as a rotating cylinder. Due to the highly reactive nature of those compositions, it is preferred that the alloys be fabricated in an inert atmosphere or in a partial vacuum.
While amorphous metal alloys are defined earlier as being at least 50~ amorphous, a higher degree of amorphousness yields a higher degree of ductility. Accordingly, amorphous metal alloys that are substantially amorphous, that is, at least 80~ amorphous are preferred. Even more preferred are totally amorphous alloys.
Because of the strength of these alloys, based on the hardness data, and their low density, these alloys a~e useful in applications re~uiring high strength-to-weight ratio such as structural materials in aerospace applications and as fibers in composite materials.
Further, the amorphous metal alloys in accordance with the invention evidence crystallization temperatures of over 400C. Thus, they are suitable in applications involving moderate temperatures up to about 400~C.
~ n arc splat unit for melting and liquid quenching high temperature reactive alloys was used. The unit, which was a conventional arc-melting button furnace modified to provide "hammer and anvil" splat quenching of alloys under ( 4~73~
inert atmosphere, included a vacuum chamber connected with a pumping system. The quenching was accomplished by providing a flat-surfaced water-cooled copper hearth on the floor of the chamber and a pneumatically driven copper-block hammer positioned above the molten alloy. As is conventional, arc-melting was accomplished by negatively biasing a copper shaft provided with a nonconsumable tungsten tip inserted through the top of the chamber and by positively biasing the bottom of the chamber. All alloys were prepared directly by repeated arc-melting of con-stituent elements. A single alloy button (about 200 mg) wasremelted and then "impact-quenched" into a foil about 0.004 inch thick by the hammer situated just above the molten pool.
The cooling rate attained by this technique was about 105 to 106C/s~c.
The impact-quenched foil directly beneath the hammer may have suffered plastic deformation after solidification.
~ However, portions of the foil formed from the melt spread away `~ from the hammer were undeformed and, hence, suitable for hardness and other ~elated tests. Hardness was measured by the diamond pyramid technique, using a Vickers-type indenter consisting of a diamond in the form of a square-based pyramid with an included angle of 136 between opposite faces.
Various compositions were prepared using the ar;c-splatting apparatus described above. A nonreactive atmosphere of argon was employed. Amorphousness was determined by X-ray diffraction. Beryllium-rich compositions, such as Ti40Be60 and Ti50Be50, formed an amorphous alloy only at very extreme quench rates (much g~eater than about 106C./sec). The eutectic composition, Ti63Be37, and a hyper-eutectic composition, Ti60Be40, easily formed totally amorphous alloys in the quench rate range of about 105 to 106C/sec.
_g_ , ~
The Ti63Be37 composition exhibited two crystal-lization peaks of about 460C~ and~545C., as determined by differential thermal analysis (DTA; scan rate 20C/min), a hardness of about 450 to 550 DPH, as measured by the diamond pyramid technique and a density of 3.83 g/cm3.
The Ti60Be40 composition exhibited a crystallization peak of 423C, as determined by DTA; a hardness of 630 DPH and a density of 3.76 g/cm3.
Other amorphous metal alloys of titanium and beryllium 1~ with one or more additional alloying elements of aluminum, boron, tantalum, and zirconium were prepared by the procedure described above. The compositions, their observed crystallization temperatures (Tc), ha~dness values (DPH) and densities ~ (g~cm ) are listed in Table I below.
:
73g~
TABLE I
Composition, atom percent Value, ~, Be Ti Al B Ta Zr _c ~ C DPH g/cm 58 2 !_ _ _ 417 674 3.80 58 - 2 - - 403 640 3.85 . ! 40 50 - 10 - _ 362 880 3.55 - - 5 - 407 810 4.28 - - 10 - 475 818 4.69 54 3 - 3 - 437 650 3.90 56 2 2 - - 455 578 3.56 58 - - - 2 419 720 3.84 - - - 10 412,437 718 4.10 ::
"'`:
, .
1~6~739L
Because of the strength of these alloys, based on the hardness data, and their low density, these alloys are useful in applications requiring high strength-to-weight ratios, such as structural applications in aerospace and as fibers in composite materials.
; An arc-splat unit for melting and liquid quenching high temperature reactive alloys was used. The unit, which was a conventional arc-melting button furnace modified to provide "hammer and anvil" splat quenching of alloys under inert atmosphere, included a vacuum chamber connected with a pumping system. The quenching was accomplished by providing a flat-surfaced water-cooled copper hearth on the floor of the chamber and a pneumatically driven copper-block hammer positioned above the molten alloy. As is conventional, arc-melting was accomplished by negatively biasing a copper shaft provided with a nonconsumable tungsten tip inserted through the top of the chamber and by positively biasing the bottom of the chamber. All alloys were prepared directly by repeated arc-melting of constituent elements.
A single alloy button (about 200 mg) was remelted and then "impact-quenched" into a foil about 0.004 inch thick by the hammer situated just above the molten pool. The cooling rate attained by this technique was about 105 to 105C/sec.
~- Hardness (DPH) was measured by the diamond pyramid technique, using a Vickers-type indenter consisting of a diamond in the form of a square-based pyramid with an included angle of 136 between opposite faces. A 50 g load was applied.
Crystallization temperature was measured by differential thermal analysis (DTA) at a scan rate of about 20C/min.
Typically, the amorphous metal alloys evidenced crystallization temperatures ranging from about 412 to 455C.
7~4 Various alloys were prepared using the arc-splatting apparatus described above. A nonreactive atmosphere of argon was employed. Amorphousness was determined by X-ray diffraction.
The compositions, their observed hardness values and densities and calculated specific strengths are listed in Table II below.
' .... .
'734 TABLE II
Composition, Atom Percent Hardness,Density, Specific Strength, Be Ti Zr Al B kg/mm2 g/cm3 cm (calculated) - 70 - - 495 5.42 28.5 x 105 - 65 - - 549 5.41 31.7 - 60 - - 572 5.40 33.2 - 55 - - 616 5.40 35.6 - 50 - - 693 5.07 42.7 - 5~ 2 - - 5.34 ~ 58 - 2 - 5.39 - 58 1 1 ~ 5-40 58 2 - - 720 3.84 58.6 56 4 - - 722 3.92 57.6 40 54` 6 - - 713 3.98 56.0 40 52 8 - - 668 4.~7 51.4 40 50 10 - - 718 - 4.10 54.8 40 45 15 - - 667 4.37 47.7 40 40 20 - - 65g 4.50 45.8 , .
40 30 30 - - 657 4.73 43.5 40 20 40 - - ~50 4.95 41.0 40 10 50 - - 637 5.21 38.2 :
40 5 55 - - 625 5.36 36.4 , "~
/
~L~64L~3~
Serial No. 238,547, Allied Chemical Corporation, File 7000-1096Ca In addition, ribbons o several compositions were fabricated in vacuum employing quartz crucibles and extruding molten material onto a quench wheel by overpressure of argon.
A partial vacuum of about 200 ~m ofHg was employed. Con-tinuous ribbons of Be40Ti54Zr6'Be40Ti52 8' 40 50 10 and Be40Zr60 were produced by this technique.
~.
. _ ;",'~
,. ,i t . .
:`
E !
These amorphous metals exist in a metastable state.
Upon heating to a sufficiently high temperature, they crystallize with evolution of heat of crystallization, and the X-ray diffraction profile changes from one having amorphous charac-`I 20 teristics to one having crystalline characteristics.
Z Novel amorphous metal alloys have been disclosed and claimed by H. S. Chen and D. E. Pol~ in U.S. Patent 3,856,513, issued December 24, 1974. These amorphous alloys have the formula MaYbZC where M is at least one metal selected from the group of iron, nickel, cobalt, chromium and vanadium, Y
is at least on~ element selected from the group consisting of phosphorus, boron and carbon, Z is at least one element selected from the group consisting of aluminum, antimony, beryllium, germanium, indium, tin and silicon, "a" ranges from about 60 to 90 atom percent, "b" ranges ~rom about 10 to 30 atom percent ~' ~
, 73~
and "c" ranges from about 0.1 to 15 atom percent. Theseamorphous alloys have been found suitable for a wide variety of applications, including ribbon, sheet, wire, powder, etc.
Amorphous alloys are also disclosed and claimed having the formula TiXj, where T is at least one transition metal, X is at least one element sele~ted from the group consisting of aluminum, antimony, beryllium, boron, germanium, carbon, indium, phosphorus, silicon and tin, "i" ranges from about 70 to 87 atom percent and "j" ranges from about 13 to 30 atom percent. These amorphous alloys have been found suitable for wire applications.
At the time these amorphous alloys were discovered, they evidenced mechanical properties that were superior to then known polycrystalline alloys. Such superior mechanical pro-perties included ultimate tensile strengths of up to 350,000 psi, hardness values (DPH) of about 650 to 750 kg/mm2 and good ductility. Nevertheless, new applications requiring improved magnetic, physical and mechanical properties and higher thermal stability have necessitated efforts to develop further compositions. More specifically, there remains a need for high strength, low density material suitable for structural applications.
SUMM~RY OF THE INVENTION
In accordance with the invention, high strength, low density amorphous metal alloys are formed from compositions of the formula BeaTibZrcXd, wherein X is at least one additional alloying element selected from the group consisting of the transition metals listed in Groups IB to VIIB and Group VII~, Rows 4, 5 and 6, of the Periodic Table and of the metalloid elements phosphorus, boron, carbon, aluminum, silicon, tin, germanium, indium and antimony; "a"
varies from 30 to 52 atom percent, "b" from 0 to 68 atom percent ~2--lQ~734 "c" varies from 0 to 70 atom percent, and "d" varies from 0 to lO
atom percent. Two species of alloy within this formula are (I) those formed from compositions having about 48 to 68 atom percent titanium, about 32 to 52 atom percent beryllium, with a maximum of up to about 10 atom percent of beryllium replaced by at least one additional alloying element, selected from the group consisting of transition metals listed in Groups IB to VIIB and Group VIII, Rows 4, 5 and 6 of the Periodic Table, and metalloid elements phosphorus, boron, carbon, aluminum, silicon, tin, germanium, indium and antimony. Preferably, amorphous titanium-beryllium base alloys are formed from compo-sitions having about 50 to 61 atom percent titanium, about 37 to 41 atom percent beryllium and about 2 to 10 atom percent of at least one element selected from the group consisting of aluminum, boron, tantalum and zirconium. Also, preferred are amorphous titanium-beryllium binary alloys formed from ; ` compositions having from about 58 to 68 atom pe~cent titanium and from about 32 to 42 atom percent beryllium. The second species (II) of compositions according to the invention are those defined within an area on a ternary diagram, having as its coordinates in atom percent Be, atom percent Ti and atom percent Zr, the area being defined by a polygon having at its corners the five points defined by ; (a) 30% Be, 0% Ti, 70% Zr tb) 50% Be, 0% Ti, 50% Zr (c) 50% Be, 40% Ti, lO~ Zr (d) 42% Be, 56% Ti, 2% zr (e) 36~ Be, 62% Ti, 2% Zr.
The alloys of the invention evidence specific strengths of about 28 to 60 x 105 cm. Also, the alloys of this invention 73~
are at least 50% amorphous, and preferably substantially amorphous, that is, at least 80~ amorphous; and most preferably about 100% amorphous~ as determined by X-ray diffraction.
The amorphous metal alloys are fabricated by a process which comprises forming a melt of the desired composition and quenching at a rate of about 105 to 106C./sec by castlng molten alloy onto a chill wheel in an inert atmosphere or in a partial vacuum.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a ternary phase diagr.am, in atom percent, : of the Ti~Be-X, system of species (I) where X represents at least one additional alloying element, depicting the glass-forming range;
` ~IG. 2 is a binary phase diagram, in atom p~rcent, - --of the Ti-Be system within species (I) depicting the glass-forming range.
FIG. 3 is a ternary phase diagram in atom percent of the Be-Ti-Zr system within species (II) depicting the glass-forming region.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the invention, high strength, low density amorphous metal alloys are formed from compositions ; of the formula BeaTibzrcxd~ wherein X is at least one additional alloying element selected from the group consisting of the transition metals listed in Groups IB to VIIB and Group VIII, Rows 4, 5 and 6, of the Periodic Table and of the metalloid elements phosphorus boron, carbon, alluminum, silicon, tin, germanium, indium and antimony; "a" varies from 30 to 52 atom 30 percent, "b" from 0 to 68 atom percent, "c" varies from 0 to 70 atom percent, and "d" varies from 0 to 10 atom percent.
~473~
The amorphous metal alloys in accordance with theinvention comprise about 30 to 52 atom percent beryllium, zero to about 68 atom percent titanium and zero to about 70 atom percent zirconium, with a maximum of up to about 10 atom percent of one additional alloying element selected from the group consisting of transition metal elements and metalloids. The transition metal elements are those listed in Groups IB to VIIB and Group ~III, Rows 4, 5 and 6 of the Periodic Table. The metalloid elements include phosphorus, boron, caebon, aluminum, silicon, tin, germanium, indium and antimony. Examples of preferred additional alloying elements include boron, aluminum, tantalum and zirconium. In a preferred species, the amorphous metal alloys have a composition consisting essentially of about 50 to 61 atom percent titanium, 37 to 41 atom percent beryllium and about 2 to 10 atom percent of at least one element selected from the group consisting of aluminum, boron, tantalum and zirconium. The purity of all elements is that found in normal commercial practice.
FIG. 1, which is a ternary composition phase diagram, depicts the glass-forming region in accordance with this species.
This region, which is designated by the polygon a-b-c-d-a, en~
compasses glass-forming compositions having high strength, good ductility and low density.
Specifically the amorphous metal alloys of the first species have a binary composition consisting essentially of about 58 to 68 atom percent titanium and about 32 to 42 atom percent beryllium. Such preferred alloys evidence high strength and low density, resulting in a high strength-to-weight ratio.
In FIGS. l and 2, the preferred range is depicted by the line a-e. As a consequence of the high strength-to-weight ratio realized for the binary system, it is preferred that any additional alloying elemen~s added have a relatively low density in order 10~73~
to retain the favorable strength-to-weight ratio. A second species (II) of alloys contemplated by the formula are defined within an area on a ternary diagram having as its coordinates in atom percent Be, atom percent Ti and atom percent Zr, the area being defined by a polygon having at its corners the five points defined by (a) 30% Be, 0% Ti, 70% Zr (b) 50% Be, 0% Ti, 50% Zr (c) 50% Be, 40% Ti, 10% Zr (d) 42% Be, 56~ Ti, 2% Zr (e) 36% Be, 62~ Ti, 2% Zr.
FIG. 3, which is ternary composition phase diagram, depicts the glass-forming region of species (II~ of the inventionO
This region, which is designated by the polygon a-b-c-d-e-a, encompasses glass-forming compositions having high strength, low density and good ductility.
Amorphous metal alloys evidencing substantial improve-ments in strength-to-weight ratios are represented by the formula Be40Ti60 xZrx, where "x" ranges from about 2 to 60 atom percent.
These alloys are depicted in the Figure by the line f-g and are preferred.
For low values of "x", that is, from about 2 to about 10 atom percent, hardness values of about 630 to 720 kg/mm2 and densities of about 3.8 to 4.1 g/cm3 are realized. While the hardness values are within the range of those of prior art amorphous alloys, the densities are considerably lower, by a factor of about 2. Since hardness is related to strength, it is evident that for low values of "x", a substantial improvement in the strength-to-weight ratio is realized. Accordingly, such compositions are especially preferred.
For higher values of "x", the hardness remains substan-tially unchanged, while the density increases to about 5.4 g/cm3, ~Gi473~
still well below that of prior art amorphous alloys. Thus, high strength to-weight ratios are retained for the entire range of compositions.
The specific strength of amorphous metal alloys is cal-culated by dividiny the hardness value (in kg/mm2) by both a dimensionless factor of about 3.~ and the density (in g/cm3).
The basis for the dimensionless factor is given in Scripta Metallurgica, Vol. 9, pp. 431-436 (1975). The high strength-to-weight properties of alloys in accordance with the invention may then be compared with those of other prior art amorphous metal alloys. For example, Pd80Si20 has a specific strength (in units of 105 cm) of 1501 and Ti50Cu50 has a specific strength of 29.6. In contrast, one of the typical preferred alloys of this invention, Be40Ti50Zr10, has a speci~ic strength of 54.8, considerably higher than that of prior art amorphous metal alloys.
In general, the amorphous metal alloys of the invention evidence specific strengths of about 28 to 60 x 105 cm.
Illustration of alloys of the invention evidencing high specific strengths are those represented by the formula given above, Be40Ti60 xZrx. Alloys within the scope of the invention evidencing lower density and the same or higher hardness values have correspondingly higher specific strengths.
Typical amorphous metal alloys of the invention evidencing good strength-to-weight ratios and exceptional ease of glass-forming behavior are represented by the formula BeyZr10O y, where "y" ranges from about 30 to 50 atom percent.
These compositions are depicted in FIG. 3 by the line a-b and are also preferred.
The amorphous metal alloys are formed by cooling a melt of the desired composition at a rate of about 105 /
~L~G~734 to 106C./sec. The purity of all compositions is that found in normal commercial practice. A variety of techniques are available, as is now well-known in the art, for fabricating splat-quenched foils and rapid-quenched continuous ribbon, wire, sheet, powder, etc. Typically, a particular composition is selected, powders or granules of the requisite elements in the desired portions are melted and homogenized, and the molten alloy i5 rapidly quenched on a chill surface, such as a rotating cylinder. Due to the highly reactive nature of those compositions, it is preferred that the alloys be fabricated in an inert atmosphere or in a partial vacuum.
While amorphous metal alloys are defined earlier as being at least 50~ amorphous, a higher degree of amorphousness yields a higher degree of ductility. Accordingly, amorphous metal alloys that are substantially amorphous, that is, at least 80~ amorphous are preferred. Even more preferred are totally amorphous alloys.
Because of the strength of these alloys, based on the hardness data, and their low density, these alloys a~e useful in applications re~uiring high strength-to-weight ratio such as structural materials in aerospace applications and as fibers in composite materials.
Further, the amorphous metal alloys in accordance with the invention evidence crystallization temperatures of over 400C. Thus, they are suitable in applications involving moderate temperatures up to about 400~C.
~ n arc splat unit for melting and liquid quenching high temperature reactive alloys was used. The unit, which was a conventional arc-melting button furnace modified to provide "hammer and anvil" splat quenching of alloys under ( 4~73~
inert atmosphere, included a vacuum chamber connected with a pumping system. The quenching was accomplished by providing a flat-surfaced water-cooled copper hearth on the floor of the chamber and a pneumatically driven copper-block hammer positioned above the molten alloy. As is conventional, arc-melting was accomplished by negatively biasing a copper shaft provided with a nonconsumable tungsten tip inserted through the top of the chamber and by positively biasing the bottom of the chamber. All alloys were prepared directly by repeated arc-melting of con-stituent elements. A single alloy button (about 200 mg) wasremelted and then "impact-quenched" into a foil about 0.004 inch thick by the hammer situated just above the molten pool.
The cooling rate attained by this technique was about 105 to 106C/s~c.
The impact-quenched foil directly beneath the hammer may have suffered plastic deformation after solidification.
~ However, portions of the foil formed from the melt spread away `~ from the hammer were undeformed and, hence, suitable for hardness and other ~elated tests. Hardness was measured by the diamond pyramid technique, using a Vickers-type indenter consisting of a diamond in the form of a square-based pyramid with an included angle of 136 between opposite faces.
Various compositions were prepared using the ar;c-splatting apparatus described above. A nonreactive atmosphere of argon was employed. Amorphousness was determined by X-ray diffraction. Beryllium-rich compositions, such as Ti40Be60 and Ti50Be50, formed an amorphous alloy only at very extreme quench rates (much g~eater than about 106C./sec). The eutectic composition, Ti63Be37, and a hyper-eutectic composition, Ti60Be40, easily formed totally amorphous alloys in the quench rate range of about 105 to 106C/sec.
_g_ , ~
The Ti63Be37 composition exhibited two crystal-lization peaks of about 460C~ and~545C., as determined by differential thermal analysis (DTA; scan rate 20C/min), a hardness of about 450 to 550 DPH, as measured by the diamond pyramid technique and a density of 3.83 g/cm3.
The Ti60Be40 composition exhibited a crystallization peak of 423C, as determined by DTA; a hardness of 630 DPH and a density of 3.76 g/cm3.
Other amorphous metal alloys of titanium and beryllium 1~ with one or more additional alloying elements of aluminum, boron, tantalum, and zirconium were prepared by the procedure described above. The compositions, their observed crystallization temperatures (Tc), ha~dness values (DPH) and densities ~ (g~cm ) are listed in Table I below.
:
73g~
TABLE I
Composition, atom percent Value, ~, Be Ti Al B Ta Zr _c ~ C DPH g/cm 58 2 !_ _ _ 417 674 3.80 58 - 2 - - 403 640 3.85 . ! 40 50 - 10 - _ 362 880 3.55 - - 5 - 407 810 4.28 - - 10 - 475 818 4.69 54 3 - 3 - 437 650 3.90 56 2 2 - - 455 578 3.56 58 - - - 2 419 720 3.84 - - - 10 412,437 718 4.10 ::
"'`:
, .
1~6~739L
Because of the strength of these alloys, based on the hardness data, and their low density, these alloys are useful in applications requiring high strength-to-weight ratios, such as structural applications in aerospace and as fibers in composite materials.
; An arc-splat unit for melting and liquid quenching high temperature reactive alloys was used. The unit, which was a conventional arc-melting button furnace modified to provide "hammer and anvil" splat quenching of alloys under inert atmosphere, included a vacuum chamber connected with a pumping system. The quenching was accomplished by providing a flat-surfaced water-cooled copper hearth on the floor of the chamber and a pneumatically driven copper-block hammer positioned above the molten alloy. As is conventional, arc-melting was accomplished by negatively biasing a copper shaft provided with a nonconsumable tungsten tip inserted through the top of the chamber and by positively biasing the bottom of the chamber. All alloys were prepared directly by repeated arc-melting of constituent elements.
A single alloy button (about 200 mg) was remelted and then "impact-quenched" into a foil about 0.004 inch thick by the hammer situated just above the molten pool. The cooling rate attained by this technique was about 105 to 105C/sec.
~- Hardness (DPH) was measured by the diamond pyramid technique, using a Vickers-type indenter consisting of a diamond in the form of a square-based pyramid with an included angle of 136 between opposite faces. A 50 g load was applied.
Crystallization temperature was measured by differential thermal analysis (DTA) at a scan rate of about 20C/min.
Typically, the amorphous metal alloys evidenced crystallization temperatures ranging from about 412 to 455C.
7~4 Various alloys were prepared using the arc-splatting apparatus described above. A nonreactive atmosphere of argon was employed. Amorphousness was determined by X-ray diffraction.
The compositions, their observed hardness values and densities and calculated specific strengths are listed in Table II below.
' .... .
'734 TABLE II
Composition, Atom Percent Hardness,Density, Specific Strength, Be Ti Zr Al B kg/mm2 g/cm3 cm (calculated) - 70 - - 495 5.42 28.5 x 105 - 65 - - 549 5.41 31.7 - 60 - - 572 5.40 33.2 - 55 - - 616 5.40 35.6 - 50 - - 693 5.07 42.7 - 5~ 2 - - 5.34 ~ 58 - 2 - 5.39 - 58 1 1 ~ 5-40 58 2 - - 720 3.84 58.6 56 4 - - 722 3.92 57.6 40 54` 6 - - 713 3.98 56.0 40 52 8 - - 668 4.~7 51.4 40 50 10 - - 718 - 4.10 54.8 40 45 15 - - 667 4.37 47.7 40 40 20 - - 65g 4.50 45.8 , .
40 30 30 - - 657 4.73 43.5 40 20 40 - - ~50 4.95 41.0 40 10 50 - - 637 5.21 38.2 :
40 5 55 - - 625 5.36 36.4 , "~
/
~L~64L~3~
Serial No. 238,547, Allied Chemical Corporation, File 7000-1096Ca In addition, ribbons o several compositions were fabricated in vacuum employing quartz crucibles and extruding molten material onto a quench wheel by overpressure of argon.
A partial vacuum of about 200 ~m ofHg was employed. Con-tinuous ribbons of Be40Ti54Zr6'Be40Ti52 8' 40 50 10 and Be40Zr60 were produced by this technique.
~.
. _ ;",'~
,. ,i t . .
:`
E !
Claims (6)
1. A high strength, low density metal alloy that is substantially amorphous, characterized in that the alloy comprises about 48 to 68 atom percent titanium and about 32 to 52 atom percent beryllium, with a maximum of up to 10 atom percent of beryllium replaced by at least one additional alloying element selected from the group consisting of the transitional metals listed in Groups IB to VIIB and Group VIII, Rows 4, 5, and 6, of the Periodic Table and of the metalloid elements phos-phorus, boron, carbon, aluminum, silicon, tin, germanium, indium and antimony.
2. The alloy of claim 1 in which said additional alloying element is selected from the group consisting of aluminum, boron, tantalum and zirconium.
3. The alloy of claim 2 in which the alloy consists essentially of about 50 to 61 atom percent titanium, about 37 to 41 atom percent beryllium, and about 2 to 10 atom percent of at least one element selected from the group consisting of aluminum, boron, tantalum and zirconium.
4. The alloy of claim 1 in which the alloy consists essentially of about 58 to 68 atom percent titanium and about 32 to 42 atom percent beryllium.
5. The alloy of claim 4 in which the alloy has the composition Ti63Be37.
6. The alloy of claim 4 in which the alloy has the composition Ti60Be40.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US51939474A | 1974-10-30 | 1974-10-30 | |
| US05/572,563 US3989517A (en) | 1974-10-30 | 1975-04-28 | Titanium-beryllium base amorphous alloys |
| US60451075A | 1975-08-13 | 1975-08-13 | |
| US05/709,028 US4050931A (en) | 1975-08-13 | 1976-07-27 | Amorphous metal alloys in the beryllium-titanium-zirconium system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1064734A true CA1064734A (en) | 1979-10-23 |
Family
ID=27504552
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA238,547A Expired CA1064734A (en) | 1974-10-30 | 1975-10-29 | High strength low density amorphous beryllium metal alloy |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1064734A (en) |
-
1975
- 1975-10-29 CA CA238,547A patent/CA1064734A/en not_active Expired
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