US1926775A - Alloy containing zirconium and tungsten for the principal constituents - Google Patents

Description

Patented ent. Ti, 11%33 NETED STATES PATENT OFFICE TUNGSTEN STI'I'UENTS AND Yoshiatsu Kamishima, Dairen, China No Drawing.

Application August 22,

Serial No. 55$,84l, and in Japan September 1 (Claim. (Cl. 75--1) This invention relates to metallic alloys, and more particularly to. an alloy in which the principal constituentsare zirconium and tungsten, the invention having for its object to provide an 5 alloy which is well suited for cutting tools, wire dies, etc.

A further object of the invention is to provide an alloy having great hardness, and the ductility of which may be increased without reduction of said hardness.

The hard metallic alloys best known at present consist of a mixture of tungsten carbide, or tungsten carbide and chromium carbide, combined with other metals, for example cobalt and iron. a

I have discovered that by adding 10- 70 parts of zirconium to a tungsten base alloy containing more than 10 parts of tungsten and metals of the iron group, such as iron, cobalt and nickel, or metals of the chromium group, such as chro mium and molybdenum, an alloy of superior hardness is obtained. I have also discovered that by adding to such alloy a small percentage of beryllium and tantalum the ductility can be increased without sacrifice of hardness.

The present invention, therefore, contemplates a metallic alloy which does not consist mainly of carbide, but owes its great hardness to the zirconium metal contained therein. Zirconium 39 as a metal itself has the hardness of 8.5 as against 10 of diamond and ranks highest among elemental metals. When melted and combined with tungsten, it becomes still harder until its hardness reaches 9. For instance, with a ferrotungsten alloy consisting-of tungsten 75%, iron 24%, carbon 0.6% and impurities it is difficult to fracture glass. However, if one melts together a mixture containing tungsten 50%, zirconium iron 19%, carbon 0.7%, and 0.3% impurities, an alloy almost as hard as diamond is produced. This hardness is due partly to the natural hardness of the metallic zirconium itself and partly to the hardness of the combined tungsten and zirconium and is quite different from the 45 hardness secured from carbide as is the case with the other alloys. The action of the zirconium prevents decomposition of the carbide, more or less of which is produced in the manufacture of the alloy according to this invention. It follows, therefore, that the hardness of the alloy is not decreased. This is one of the important features of the present invention. The following is an example of carrying thi invention into practice: Tungsten ore or ferro-tungsten and zirconium ore are pulverized and carbon added thereto, the

proportions of the mixture being tungsten 50%,

zirconium 30% and iron 20%. The mixture is then melted in an electric furnace, whereupon the impurity, namely silicon, will volatilize, leaving the above metallic alloy in the furnace. The product thus obtained may be made into ingots for use in making edged tools, or may be pulverized and made into any desired shape by a sintering process.

Inasmuch as the alloy according to this invention is-obtained by melting, there is no necessity for mixing the. ingredients as fine powder, unlike the known product obtained by combining with carbide (for example wi-dia). Moreover, if iron, cobalt, molybdenum, nickel, chromium, aluminum and manganese are added to the alloy manufactured according to this invention, the ductility will be increased, but the hardness will be decreased, so that the quantity of theseingredients must be regulated according to the purpose for which the alloy is to be used. However, if beryllium 05-10% and tantalum 05-10% are added to the alloy the ductility of which is to be increased by the addition of iron, cobalt and molybdenum, the hardness of the alloy will be maintained at the highest degree notwithstanding the increase in ductility.

Alloys according to this invention,-for instance, alloys of tungsten and zirconium unmixed with other irnpuritie s,-are not oxidized even at the melting point of 2400 C. (It is Well known that an alloy mixed with tungsten only is considerably oxidized on exposure to the atmosphere.) This resistance to oxidation is chiefly due to the action of the zirconium. This non-oxidizing property and high melting point makes this alloy ideal for an electric furnace producing high heat as compared with platinum,

which melts at 1750 C. Moreover, this alloy has electrical resistance eighty times as high as copper, that is to say, far greater than platinum, which has electrical resistance ten times as high as copper. Consequently, the alloy is of great utility as electrical resistance wire.

I claim as my invention:

A metal alloy consisting of 30% of zirconium, 50% of tungsten and 20% of iron.

YosHIA'rsU KAIVHSHIMA.