Effect of various carbides on the dissolution behavior of Ti(C0.7N0.3) in a Ti(C0.7N0.3)-30Ni system

HfC, TaC, or WC were individually added to a Ti(C0.7N0.3)-30 wt% Ni system, in order to investigate micro structural changes and the dissolution behaviors of Ti(C0.7N0.3) and the carbides. Of these systems, the Ti(C0.7N0.3)-WC-Ni system proved to be the most favorable for the refinement of microstructure. The fraction for the cross-sectional area of the Ti(C0.7N0.3) cores, which is related to the amount of Ti(C0.7N0.3) dissolved, increases and the thickness of solid solution rims decreases in the order of HfC, TaC, and WC added, This finding indicates that the dissolution rate of Ti(C0.7N0.3) in a Ni melt is the lowest when WC is added. In addition, it was found that the average dissolution rate of Ti(C0.7N0.3) in the HfC-containing system is similar to1.6 and 1.9 times higher than those for Ti(C0.7N0.3) in the TaC- and WC-containing systems at the same sintering conditions. Further, the dissolution rates of TaC and WC were similar to80% of the rate found for HfC during the formation of the outer rim. (C) 2001 Elsevier Science Ltd. All rights reserved.