Influence of hot isostatic pressing on microstructures and properties of NiAl/Cr(Mo)-TiC in-situ multiphase composites

A novel in-situ multiphase NiAl-based composite was investigated on its microstructures and properties influenced by HIP treatment. In the as- processed composites, a fine array of NiAl precipitates was found to be distributed in Cr(Mo) phase. TiC particles tended to segregate at grain or phase boundaries. In addition, a number of dislocations were observed to exist in NiAl grains meanwhile fewer in Cr(Mo) grains. Little change in the morphology was found except that nearly fully densification was achieved. Some changes in microstructures were notable including coarsening of NiAl precipitates in Cr(Mo) phase and increase in dislocation density in NiAl phase. After HIP, the strength of the composites increased significantly compared with the as-processed composites. The reason for the enhanced strength of the composites is also discussed.