«VNIIINSTRUMENT» Russian Research & Development Tooling Institute, Moscow, Russia

V. A. Falkovskiy, Chief Researcher, e-mail: vafalk@rumbler.ru
G. V. Borovskiy, Chief Executive Officer

S. U. Molodyk, Head of Department
S. K. Belyaev, Head of Laboratory

OJSC «Kirovgrad Hard Alloys Plant», Kirovgrad, Russia

L. I. Klyachko, Scientific Consultant

The scientific review is devoted to the global achievements in developing the WC—Co hard alloys with gradient structure. The article epitomizes the history of the hard metals development with gradient structure. Various kinds of gradient structures were considered:
– differing by variable structure in volume or on a height of a product;
– changing of an alloy microstructure (granularity or structure of phases) in volume or on a thickness of a product;

– presence of the alloy phases` layers, which were specified by a thickness.

Depending on appointment, layers can be thick, with the size of 10 microns and more, and thin, with the size of less than 5 mic rons. Phase layers represent the films of cobalt or carbide phases of a various thickness. Results of experimental researches were discussed for the creation of a functional gradient for the account of carbide phase of a various content as well as of the gradient structure. The gradient structure was created by the various dispersibility of the carbide phase. The mechanism of a gradient formation was also discussed, particularly: the cobalt migration in the sintered product. The basic attention was given to the hard alloys, which were intended for equipment of the cutting and mountain-chisel tool. In this kind of tool, the global volume of application of WС – Co alloys is about 85–90% from the total amount of hard alloys` usage. During the cutting and drilling, the hard alloys with a gradient structure, provided an increasing of durability of the tool from 2 to 4 times.

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