Elevated temperature compressive behavior of in-situ multiphase composites NiAl/Cr(Mo)-TiC

A new multiphase composite based on intermetallic NiAl was fabricated using reaction synthesis method. The TiC particles were formed in-situ in the matrix and most of them accumulated at phase or grain boundaries. Its elevated temperature compressive behavior was investigated. The flow stresses of the composites generally decreased with increasing temperature and/or decreasing initial strain rate. It was found that the deformation feature of the composites could be adequately described by standard power law which is usually used to characterize creep behavior for various metallic materials. Thus the stress exponent n as well as activation energy Q were calculated by fitting the experimental data to the power-law and temperature-compensated power-law equations. The deformation behavior was discussed in comparison with other NiAl matrix composites. The high temperature strengths of the composites, especially the 16wt.%TiC particulate reinforced one, are superior to monolithic NiAl and a composite NiAl-20vol.%TiB2 at slower strain rate. The strengthening mechanisms were discussed preliminarily. However, when compared with directionally solidified NiAl/Cr(Mo), the present composites are relatively weak. An explanation for the weakness is given in the paper. (C) 1998 Elsevier Science S.A. All rights reserved.