|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||GAT-2017 (Gamma Alloys Technology - 2017)
||High Temperature Mechanical Properties of Polysynthetic Twinned TiAl-Nb Alloys
||Zhixiang Qi, Guang Chen, Yingbo Peng, Gong Zheng
|On-Site Speaker (Planned)
The mechanical properties of TiAl-Nb PST single crystals were investigated at high temperatures. The results showed that BDTT of the TiAl-Nb single crystals was in the range of 950℃ to 1000℃. Because of Nb’s enrichment in γ phase, mechanical twinning formed easily during deformation, which turned out to be benefit for the improvement of high temperature strength. The α2/γ and γ/γ interfaces are also responsible for the excellent strength by impeding the dislocations slip. The strengthening effect of these interfaces is in the order of twins/matrix＞α2/γ＞γ/γ. At 1000℃, the twins become instable and dislocations found exist in the twin boundary and cause the superplastic phenomenon. For the reason that the nucleation of twins is much higher than that for the growth of twins, the stress-stain curve of the PST single crystals at 1000℃ showed oscillations phenomenon, another factor is the cyclic depinning–repinning process from the effect of dislocations and twins.
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