Mechanical alloying of TiC/M2 high speed steel composite powders and sintering investigation

TiC/M2 high speed steel composite powders were prepared by mechanical alloying. Particle characterization and sinterability of the composite powders were investigated. A relatively small particle size and a narrow particle size distribution were obtained after 20 h of milling. Observations of polished cross-section showed uniform distribution of reinforcement particles. The powders were hot compacted with PAN250 binder. The compact was then debound and sintered. DTA analysis of the debound part showed that liquids started to appear after 1040.7°C. As liquids have greater opportunity to form at the interfaces between the reinforcement particles and the matrix as well as the interior layer surfaces in the big individual composite particles, less capillary force acts on the periphery of the composite particles. Thus, the supersolidus liquid phase sintering of the composite materials was hindered. Microstructure analysis showed the formation of MC carbides with high content of TiC particles. Grain growth and microstructure coarsening were retarded by the mixed phase microstructure.