High-temperature deformation behavior of Ti-TiBw in-situ metal-matrix composites

In developing titanium-based materials for high-performance structural applications, the focus has been on discontinuously reinforced titanium-matrix composites that are based on the in-situ creation of TiB whiskers. This article presents the elevated-temperature compressive flow properties of Ti-TiBw composites as a function of temperature (from 973 K to 1,273 K), strain rate (from 10−5 to 10−3s−1), and the TiB whisker content (commercially pure titanium and composites with 30 to 86 vol.% TiBw). In both the commercially pure titanium and the TiB-whisker-containing titanium composites, flow stress increases with increasing strain rate and decreasing test temperature. In this study, flow stress increased with increasing volume fraction of TiB at a given temperature and strain rate. The composite containing 86% TiBw showed significantly higher elevated-temperature strength when compared to the other composites. The composites exhibit systematic trends in the variation of work-hardening behavior (in terms of work-hardening exponent, n, and work-hardening rate, dσ/dɛ) and the strain-rate dependence.