热暴露对激光沉积Ti60A高温钛合金组织性能影响

Effect of Thermal Exposure on Microstructure and Mechanical Properties of Laser Deposited Ti60A High Temperature Titanium Alloy

摘要:

对比研究了激光沉积Ti60A高温钛合金经600 ℃, 100 h的恒温热暴露和循环热暴露后显微组织、拉伸性能及断口形貌。结果表明，恒温热暴露后α相体积分数略有增大。循环热暴露后β相体积分数显著减小，α相体积分数增加约12%。这2种热暴露后合金中Ti3Al共格有序相和100~150 nm的六方S2型椭球状硅化物(TiZr0.3)6Si3的析出基本一致，拉伸性能均明显下降，尤其是循环热暴露后的塑性几乎丧失，这与合金组织在循环热应力作用下的显著变化密切相关

Abstract:

Microstructure and tensile properties of laser deposited Ti60A high temperature titanium alloy was investigated after 600 oC, 100 h isothermal exposure and cyclic thermal exposure. Results indicate that the volume fraction of α phase increases slightly after isothermal exposure. While the broken β and coarsened α platelets occur in the alloy after cyclic thermal exposure and the volume fraction of α phase even increases about 12%. The precipitation of fine ordered coherent Ti3Al and 100~150 nm hexagonal quaxi-S2 type ellipsoidal silicide (TiZr0.3)6Si3 is nearly the same in the alloy after isothermal or cyclic thermal exposure. The tensile properties of the alloy are significantly decreased after thermal exposure. In particular, the ductility of the alloy after cyclic thermal exposure is almost lost, which is closely related to the obvious microstructural changes produced by cyclic thermal stress