Reactive sintering of WC-Ni-Co-Cr-Ti-Al cemented carbides and precipitation of gamma prime in their metallic binder phases

Abstract

Cemented carbides processed from WC-Ni-Co-Cr3C2-TiAl3 powder mixtures by HIP after sintering present a homogeneous precipitation of gamma prime in their metallic binder phases. Other reaction products include alumina precipitates and (Ti-x,W1-x)C mixed carbides. The formation of these phases is consistent with the highly exothermic reactions detected by DSC during the heating ramp of the sintering cycle. The amount of alumina and gamma prime phases present in the sintered materials depends on the oxygen content of the powder mixtures. Refinement of gamma prime precipitates depends critically on the cooling rate after HIPing. Nanoindentation experiments have confirmed the presence of age hardening effects of samples which were previously solution treated. As expected, gamma prime precipitation is induced at lower temperatures in compositions with higher Al contents in the binder phase.