Effects of Chromium and Nitrogen Contents on Microstructural Changes in TiC Particles in (α plus β)- and β-Titanium Matrix Composites

New composite materials with high strength and toughness are expected to be obtained from titanium alloys by a-titanium precipitation in ceramic particles dispersed in a matrix. In this study, a series of Ti-Cr-C-N alloys were prepared, and the effects of chromium and nitrogen contents on the microstructural changes in the TiC particles were revealed in (alpha + beta)- or beta-titanium alloys, alpha-Titanium precipitation in the TiC particles was observed when the nitrogen content was more than 2 at% and the chromium content was less than 11 at%. The mechanism of and the conditions for a-titanium precipitation are discussed in terms of the crystallographic relationship between a-titanium and metastable Ti2C. [doi:10.2320/matertrans.M2012127]