冲击拉伸加载下等轴TiAl的微观组织演化行为

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Through study on the mechanical behavior and deformation mechanism of Ti-46.5Al-2Nb-2Cr alloy at different temperature and strain rate,the effects of strain rate on the deformation mechanism of isometric TiAl（NG TiAl） were explored.The dynamic mechanical behavior of TiAl was tested by tensile impact loadings experiment.The results show that the strength of TiAl is strain rate and temperature dependent.The dynamic strength of TiAl is higher than that under quasi-static loadings but is not sensitive to strain rate under high strain rate loading range of 320~1 350 s-1.The brittle-to-ductile temperature（BDTT） under high strain rate loadings is higher than that under quasi-static loadings.TEM investigation indicates that deformation twinning and/or stacking fault are the main deformation modes of isometric TiAl under high strain rate loadings while the dislocation movement is another mechanism under quasi-static loadings.通过对等轴组织的Ti-46.5Al-2Nb-2Cr在不同温度和应变率下的力学行为和变形机理研究,揭示应变率对其变形机理的影响。利用冲击拉伸实验研究等轴TiAl在不同温度下的动态力学行为。研究结果表明：等轴TiAl的强度是与温度和应变率相关的;动载下的强度明显高于静载下的强度,但在高应变率范围内（320~1350s-1）无明显的应变率相关性;动载下的韧脆转变温度较静载下的韧脆转变温度高。透射电镜（TEM）分析表明高应变率加载下,等轴TiAl的变形主要受层错和孪生机制的控制,而在准静态加载条件下,位错运动机制是主要的变形方式。