Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/007—Alloys based on nickel or cobalt with a light metal (alkali metal Li, Na, K, Rb, Cs; earth alkali metal Be, Mg, Ca, Sr, Ba, Al Ga, Ge, Ti) or B, Si, Zr, Hf, Sc, Y, lanthanides, actinides, as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/07—Alloys based on nickel or cobalt based on cobalt
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys

Definitions

• the present invention relates to an alloy and, more particularly, to a non-ferrous alloy which at relatively high temperatures will resist oxidation and possess a high creep strength.
• alloys available up to now for the above-indicated purposes are of such quality that, for instance, induction heating elements made thereof cannot be used at temperatures exceeding 1350 C. and thus, the alloy of the present invention because of its high creep strength and resistance to oxidation even at temperatures of 1400 C. or higher is particularly suitable for the manufacture thereof of heating elements for electromagnetic induction heating devices.
• the present invention contemplates a highly temperature resistant alloy, the alloy consisting essentially of 21% to 35% aluminum, to 4% copper, 0% to 4% of at least one metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium, the balance being at least one metal selected from the group consisting of nickel and cobalt, wherein in the absence of copper said at least one metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium is present in an amount of at least 0.2%, and in the absence of said at least one metal selected from the group con sisting of tungsten, molybdenum, vanadium and chromium said copper is present in an amount of at least 0.2%.
• alloys according to the present invention significantly exceeds the heat resistance of alloys conventionally used for similar purposes.
• the alloys according to the present invention include the following ranges of composition wherein, as throughout this specification, all percentage figures are percent by weight: 21 to 35 percent of aluminium, 0.2 to 4 percent of copper and the remainder principally at least one of the metals nickel and cobalt; Preferably and especially for the most effective alloys, the composition should be kept within the ranges 21.8 to 32.8 percent aluminium, 0.2 to 4 percent copper and the remainder at least one of nickel and cobalt.
• the present invention is concerned with a refractory, non-ferrous alloy which comprises at least three metals, namely aluminum with or without Cu and at least one metal each of the two groups described above.
• the alloy of the present invention is composed of aluminum, nickel and copper and contains between 21.8% and 32.8% of aluminum; between 67% and 78% of nickel; and between 0.2% and 4% of copper.
• the alloy of the present invention is composed of aluminum, cobalt and copper and contains aluminum in an amount of between 2l.8% and 32.8%; cobalt in an amount of between 67% and 78%; and copper in an amount of between 0.2% and 4%.
• Another preferred alloy according to the present invention is composed of a mixture in any proportion of the aluminum nickel copper alloy and the aluminum cobalt copper alloy described above.
• the greater portion of the alloy is principally one or more of nickel and cobalt. This is noted specifically because, while desiring the purest raw materials in the production of these hightemperature alloys there is some limited permissibility of impurities and remainders of deoxidizing additions such as Fe, Mg, Si, Mn, etc. In general the total of such elements should not exceed one percent.
• the alloy of the present invention may contain inclusions of oxides of its constituents, particularly of mixed oxides, for instance of A1 0 and NiO, or A1 0 and C00. These oxides may develop or be developed during the course of melting and alloying or subsequently by exposure to an oxidizing atmosphere at elevated temperature. Specifically, good results have been obtained with a total oxide content of up to 1000 ppm. in the form of such mixed oxides.
• the copper in all of the above-described compositions may be completely or partially replaced by one or more of the metals molybdenum, tungsten, vanadium and chromium within the indicated proportions.
• the alloy contains in addition to aluminium and nickel or cobalt, copper and at least one of the metals molybdenum, tungsten, vanadium and chromium.
• the alloys of the present invention may be advantageously produced by a method according to which first the aluminium and copper are melted together and thereafter the remaining constituents of the alloy are successively introduced while simultaneously the temperature of the molten metal is raised.
• the operation is advantageously effected in an oxidizing atmosphere. If there are more than one remaining constituent to be introduced, then these remaining constituents preferably are introduced in such sequence that the melting point of the molten metal mixture is prorgessively raised by the introduction of the remaining constituents.
• the alloy according to the present invention may be considered a derivative of stoichiometric alloys of aluminium with nickel and/or cobalt.
• alloys consisting essentially of two constituents, due to their high brittleness are not suitable for industrial use at high temperatures.
• At least a third or also a fourth or more constituents i.e., by forming for instance a ternary or quaternary alloy of the qualitative and quantitative composition described above, an alloy is obtained which possesses the resistance to oxidation which is shown by the above-mentioned binary, stoichiometric alloy, but very importantly overcoming the brittleness of this stoichiomertic alloy. Furthermore, by the inclusion of oxides of such constituents, the creep strength of the alloy is improved.
• the alloy of the present invention is preferably prepared by first melting the most fusible constituents of the alloy together and thereafter, in a second melting stage, to add the other constituents, particularly cobalt and/ or nickel, at a higher temperature, during which secnd stage the metal is homogenized by stirring.
• the process of the present invention is efiiciently performed by heating the alloy constituents by induction.
• an oxidizing atmosphere such as air, oxides of aluminum and nickel and/ or cobalt, mainly mixed oxides of the type Al,O NiO or will be formed and remain in the alloy.
• alloys will be obtained suitable for use at a maximum working temperature of at least 1400 C., while alloys within the percentage limits of the preferred ranges will be suitable for industrial use at temperatures of 1500 C. and even higher.
• Example 1 In an induction heated crucible in contact with the surrounding air, a liquid alloy is produced composed of 30% A1, 69% Ni, 1% Cu and 900 p.p.m. of oxides of these metals. With the help of a quartz tube of 4 mm. diameter which is subjected to a progressive partial vacuum, several samples are lifted from the metal bath in the form of small bars.
• the thus-formed small bar is heated to 1535 C. and thereafter, while this temperature is maintained, an electric current of 315 amperes and 1.56 volts is passed through the bar for a period of 169 hours during which no recognizable change takes place in the bar.
• the weight of the bar does not change in an appreciable manner which proves that the metal is not oxidized except possibly to an extremely low degree.
• the resistivity of the alloy at 1535 C. was determined to be 49.5 X ohm-centimeter.
• Example 2 An alloy of the composition Al 29%, Co 70%, Cu 1%, and containing 800 p.p.m. of oxides of these metals is produced in a heated crucible in contact with the surrounding air. In the manner described in Example 1, small sample bars are withdrawn from the molten metal.
• the sample bars are then heated at 1620 C. and at that temperature an electric current of 315 amperes is passed through the bars for an entire week. Thereafter, no noticeable change is found in the composition of the bars. Particularly their weights have not changed in an appreciable manner.
• the alloy composition of the present invention is entirely novel and can be used at temperatures which are more than 50 C. higher than those at which the conventional alloys lose their usefulness.
• the difference of more than 50 C. is very important and one cannot ignore that the calories made available for heat transfer at high temper'atures are extremely valuable. It will be understood that the alloy of the present invention is of great interest to the industry in connection with electric resistance heating arrangement.
• this interposed material will consist of small amounts of oxides of the alloy forming metals. These oxides have very little power of adhesion and, consequently, there will be little cohesion between the crystals of the binary alloy.
• These crystals will consist of for instance Al-Ni formed of a solid solution which may contain an excess of either nickel or aluminum, depending on whether the nickel content is higher or lower than 68%.
• Al-Co crystals are formed of the solid solution whereby, depending on whether the cobalt is present in an amount of more or less than 64%, an excess of nickel or cobalt will remain.
• these additional metals will be located at the interfaces between the Al-Ni or Al-Co crystals. Since the power of adhesion of these additional metals in contact with the binary crystals is much higher than that of the oxides, the presence of these additional metals will greatly increase the cohesion of the crystals and thus of the alloy.
• the adhesive forces of the material at the interfaces of the crystals seem to be of decisive importance for the cohesion and thus the mechanical characteristics in the alloy.
• These forces of the oxides are small while, in contrast thereto, the metals which are added to the binary alloy in accordance with the present invention, namely copper and/or at least one metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium greatly increase the cohesive forces between the interfaces of the binary crystals.
• Example 3 An alloy of the composition A1 29.5%, Ni 70%, Cr 0.5% and containing 850 p.p.m. of oxides of these metals is produced in an induction heated crucible in contact with the surrounding air. In the manner described in Example 1, with the help of a quartz tube of 3.5 mm. inner diameter, several samples are lifted from the metal bath in the form of small bars.
• the sample bars are then heated at 1480 C. and at that temperature, an electric current of 270 amperes and 1.54 volts is passed through the bars for a period of 56 hours.
• the resistivity of the alloy calculated at 1480 C. equals 56.8 10' ohm centimeter. No change in the condition of the alloy bar could be found after the above described 56 hours passage of electric current therethrough.
• Example 4 An alloy of the composition: A1 30.8%, C0 68%, M0 0.4%, Cu 0.8%, and containing 600 p.p.m. of oxides of these metals is produced in contact with the surrounding air. With the help of a quartz tube having an inner diameter of 3.5 mm. and in the manner described in Ex ample 1 small sample bars are withdrawn from the molten metal.
• the sample bars are then heated to 1570 C. and at that temperature an electric current of 3 30 amperes and 1.68 volts is passed through the sample bars.
• the resistivity of the alloy at 1570" C. is 52x10 ohm-centimeter.
• Example 5 An alloy of the composition: Al 30%, Ni 69%, Cu 1% and about 60 p.p.m. of oxides of these metals is proucked in a protective argon atmosphere in order to keep the oxide content as low as practically possible.
• a high temperature resistant alloy consisting of 21% to 35% aluminum, an amount not exceeding 4% of a substance selected from the group consisting of copper and at least one metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium, the balance being at least one metal selected from the group consisting of nickel and cobalt, wherein (a) in the absence of copper, at least one metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium is present in an amount of at least .2%,
• a highly temperature resistant alloy as defined i1. claim 1, and consisting essentially of 29% aluminum, cobalt and 1% copper.
• a highly temperature resistant alloy according to claim 1 being free of nickel and including 21.8% to 32.8% aluminum and 67% to 78% cobalt.
• a high temperature resistant alloy said alloy consisting of 21% to 35% aluminum, between 0.2% and 4% copper, the balance being cobalt.
• a high temperature resistant alloy consisting of 21% to 35% aluminum, between 0.2% and 4% of at least one metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium, the balance being nickel.
• a high temperature resistant alloy consisting of 21% to 35% aluminum, between 0.2% and 4% of at least one metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium, the balance being cobalt.
• a high temperature resistant alloy consisting of 21% to 35% aluminum, at least 0.2% of copper, at least 0.2% of a metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium, the combined amount of said copper and said at least one metal not exceeding 4%, the balance being nickel.
• a high temperature resistant alloy consisting of 21% to 35% aluminum, at least 0.2% of copper, at least 0.2% of a metal selected from the group consisting of tungsten, molybdenum, vanadium and chromium, the combined amount of said copper and said at least one metal not exceeding 4%, the balance being cobalt.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
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• Manufacture And Refinement Of Metals (AREA)

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Citations (3)

• 0
  • BE BE639059D patent/BE639059A/xx unknown
• 1962
  • 1962-11-09 FR FR914915A patent/FR1346453A/fr not_active Expired
• 1963
  • 1963-10-14 GB GB40400/63A patent/GB1022001A/en not_active Expired
  • 1963-11-06 DE DE19631458412 patent/DE1458412A1/de active Pending
• 1966
  • 1966-01-27 US US523256A patent/US3329498A/en not_active Expired - Lifetime

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