A simple method for evaluating cemented carbides
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w h e r e A and B are constants. The significance of this result is that it can be employed to quickly classify experimental carbide/binder combinations according t o t h e i r potential as cutting tool materials having both high hardness and good resistance t o impact. Thus, a few simple measurements to establish the constants A and B appropriate t o the c a r b i d e / binder combination under investigation allow a r e a d y comparison t o be made with another system for which the constants have previously been established. C OMMERCIAL cemented carbide cutting tools, such as those used for rock drilling and machine tool applications, normally consist of two components, a hard transition-metal carbide phase which provides abrasion resistance and cutting action and a r e l a tively ductile m e t a l phase which functions as a binder for the carbide particles and provides the impact resistance necessary to r e s i s t mechanical shock. Because cutting tools of this type are multicomponent systems, t h e i r properties are expected to be functions of numerous parameters, such as carbide g r a i n size, shape and distribution, carbide-to-binder ratio, carbide hardness, binder hardness, e t c . The many variables involved have led t o difficulties in devising test methods suitable for use in p r o g r a m s concerned with the development of improved cutting tool materials. Thus, t o determine whether a particular combination of a hard phase and a binder phase in an experimental m a t e r i a l is superior t o that in a conventional cutting tool, a l a r g e s e r i e s of tests measuring hardness and fracture properties is p r e s ently r e q u i r e d in which numerous parameters such as g r a i n size, carbide-to-binder ratio, e t c , a r e v a r i e d separately. Only when this is done, is it possible t o separate out the influence of those parameters that are c o m m o n t o b o t h systems, and thereby determine whether one carbide/binder combination is superior t o the other. Clearly, a method that would simplify this procedure could be of considerable benefit t o the cutting tool industry. In an ongoing program, attempts a r e b e i n g made t o exploit the results of p r i o r studies at these laborat o r i e s which have demonstrated that considerable control can be exercised over the mechanical properties of the transition m e t a l carbides by alloying two or more monocarbides in proportions that are d e t e r m i n e d by an understanding of t h e i r electronic 1 and crystallographic 2 structure. Specifically, t h e s e elR. K. VISWANADHAM and J. D. VENABLES are ResearchScientist and Senior Research Scientist, respectively, Martin Marietta Laboratories, Baltimore,MD21227. Manuscript submitted April 16, 1976. METALLURGICAL TRANSACTIONS A
forts have led to the preparation of (Ti, V)C alloy carbides 3 having properties that make them candidates for cutting tool applications .4,5 Therefore, t o fully det e r m i n e t h e i r suitability for this purpose, the p r o p e r t i e s of "cemented alloy c a r b i d
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