Revisiting the Possibility of Formation of Hard Alloys from Powder Mixtures of Carbides with Metals by Explosive Compacting without Sintering

Abstract

The results of experimental investigations into the possibility of formation of consolidated power hard alloys by the explosive compacting method without subsequent sintering are presented. Carbides of tungsten (WC), chromium (Cr3C2), and silicon (SiC) are used as main carbide components, and titanium, nickel, and copper serve as a metallic binder. The compression pressure of the powder mixture in shockwaves during the explosive compacting is varied in a range from 5 to 16 GPa, and the heating temperature is varied from 250 to 950°C. The structure, chemical composition, and phase composition are investigated using optical (Axiovert 40MAT, Carl Zeiss), scanning electron (FEI Versa 3D), and transmission electron (FEI Titan 80-300, Tecnai G2 20F) microscopes. It is shown that powder compositions with the titanium binder are densified substantially better than mixtures with copper or nickel. The hardness of materials after the explosive compacting reaches 1200 HV. The range of temperatures corresponding to (0.35–0.4)tm (where tm is the absolute melting point of the main alloy carbide), the cleavage character of the samples changes from intercrystallite to transcrystallite when passing through it. It is revealed that this is associated with the formation of strong boundaries between carbide particles and metallic matrix, which represent interlayers with a thickness of the order of 80–100 nm with its proper crystalline structure differing from the structure of main alloy components.