Microstructural and Mechanical Characteristics of in Situ Synthesized Chromium-Nickel-Graphite Composites

Cr-C-Ni composites were synthesized in situ from elemental powders of Cr, Ni and C by high energy milling followed by reactive sintering. The milled powders with the grain size in nano-scale were pressed to compacts and sintered. During the thermal treatment that was performed after the pressing the chromium carbide was formed first and then the Cr3C2-Ni cermets were sintered in one cycle. The interface between the binder phase and the carbide grains of the in situ composite has a good bonding strength as it is not contaminated with oxidation films or other detrimental surface reactions. The microstructure of such cermets is fine-grained and more homogeneous than that of cermets produced by conventional method. As a result the cermets have higher hardness, transverse rupture strength and 1.2-2 times higher wear and erosion resistance.