Processing and mechanical properties of Ti3SiC2: II, Effect of grain size and deformation temperature

Abstract

In this article, the second part of a two-part study, we report on the mechanical behavior of Ti3SiC2. In particular, we have evaluated the mechanical response of fine-grained (3-5 μm) Ti3SiC2 in simple compression and flexure tests, and we have compared the results with those of coarse-grained (100-200 μm) Ti3SiC2. These tests have been conducted in the 25°-1300 °C temperature range. At ambient temperature, the fine- and coarse-grained microstructures exhibit excellent damage-tolerant properties. In both cases, failure is brittle up to approximately 1200 °C. At 1300 °C, both microstructures exhibit plastic deformation (>20%) in flexure and compression. The fine-grained material exhibits higher strength compared with the coarse-grained material at all temperatures. Although the coarse-grained material is not susceptible to thermal shock (up to 1400 °C), the fine-grained material thermally shocks gradually between 750° and 1000 °C. The results presented herein provide evidence for two important aspects of the mechanical behavior of Ti3SiC2: (i) inelastic deformation entails basal slip and damage formation in the form of voids, grain-boundary cracks, kinking, and delamination of individual grains, and (ii) the initiation of damage does not result in catastrophic failure, because Ti3SiC2 can confine the spatial extent of the damage.