Hard metal alloy with surface region enriched with tantalum, niobium, vanadium or combinations thereof and methods of making the same

A method of producing a cemented carbide hard metal alloy having a surface region enriched with at least one of the carbides, nitrides and carbonitrides of tantalum, niobium or vanadium or combinations thereof comprising:

• (a) depositing by chemical vapor deposition a layer containing at least one compound selected from titanium carbide, titanium nitride and titanium carbonitride on the surface of a cemented carbide hard metal alloy to a thickness of about 1 to about 5 microns, said cemented carbide hard metal alloy comprising (i) a first component being at least one of the carbides, nitrides and carbonitrides of tantalum, niobium and vanadium or combinations thereof in an amount of at least 2.5% by weight, (ii) at least one binder metal selected from the group consisting of cobalt, nickel, iron-nickel and iron and (iii) optionally, a second component selected from titanium carbide, titanium nitride, titanium carbonitride, zirconium carbide, zirconium nitride and zirconium carbonitride such that the atomic % ratio of the optional second component to the first component is in the range of from 0 to about 1.5;
• and
• (b) heating the layered hard metal alloy to a temperature of about 1370.degree. C. to about 1450.degree. C. for about 6 to 2 hours to form said enriched surface region having a thickness of about 4 to 6 microns, wherein the amount of said first component in said surface enriched region is at least 8% by weight.