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 boundari es. Its elevated temperature compressive behavior was investigated. Th e flow stresses of the composites generally decreased with increasing temperature and/or decreasing initial strain rate. It was found that t he deformation feature of the composites could be adequately described by standard power law which is usually used to characterize creep beh avior for various metallic materials. Thus the stress exponent n as we ll 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, e specially the 16wt.%TiC particulate reinforced one, are superior to mo nolithic NiAl and a composite NiAl-20vol.%TiB2 at slower strain rate. The strengthening mechanisms were discussed preliminarily. However, wh en compared with directionally solidified NiAl/Cr(Mo), the present com posites are relatively weak. An explanation for the weakness is given in the paper. (C) 1998 Elsevier Science S.A. All rights reserved.