Effect of Ni Contents on Microstructures and Mechanical Properties for (Ti_0.8Mo_0.2)C-Ni Cermets

Abstract

The (Ti_0.8Mo_0.2)C-xNi cermets (x = 10, 20, 30 and 40 mass%) were prepared by two milling processes; first, the (Ti_0.8Mo_0.2)C produced by mechanical alloying of Ti, Mo and C powders (Process I). Second, mechanical alloyed (Ti_0.8Mo_0.2)C and commercial Ni powders mixed by tumbling ball milling (Process II) for 72 h. On (Ti_0.8Mo_0.2)C-40Ni, the milling time of Process II was 96 h in addition of 72 h. The Vickers hardness with fracture toughness and the quantitative microstructural parameters were measured and analyzed. The relationship between fracture toughness and hardness for the cermets was on the fitted curve derived from the previous data for the cermets, except for the case of (Ti_0.8Mo_0.2)C-40Ni for 72 h, which is lower fracture toughness than that for the previous works and (Ti_0.8Mo_0.2)C-40Ni for 96 h. The contiguity of the samples tend to increase with increasing hard phase contents except for the case of (Ti_0.8Mo_0.2)C-40Ni for 72 h, which is higher than those of (Ti_0.8Mo_0.2)C-40Ni for 96 h. On the other hand, the coefficient of variation for hard phase of the both (Ti_0.8Mo_0.2)C-40Ni were almost same.