热暴露对TC11钛合金断裂行为的影响

The influence of high temperature exposure on fracture behaviors of TC11 titanium alloy

对TC11钛合金经不同温度和时间热暴露后的拉伸性能进行了考察,对不同热暴露后断裂行为的变化及其原因进行了分析研究。结果表明,热暴露温度不高于550℃,热暴露后的室温拉伸性能与未处理时相差不大,断面由纤维区和剪切唇区组成,无放射区;热暴露温度高于550℃时,热暴露后TC11钛合金的塑性急剧下降,断面由放射区和剪切唇区组成,无纤维区,且放射区收敛于断面上靠近试样表面附近,点源。放射区微观上可见韧窝、准解理及沿相界、晶界分离的混合形貌特征,不同于纤维区的等轴韧窝形貌,且剪切唇区可见解理、准解理脆性断裂特征。热暴露后TC11钛合金这种宏微观断裂行为的变化是由试样表面氧污染层的缺口效应、针状α2(Ti3Al)相的析出以及次生α与β的长大所致。

The tensile properties at room temperature of TC11 titanium alloy after high temperature exposure with different temperature and time investigated. The variation and cause of fracture behaviors for TC11 titanium alloy after different high temperature exposure were analyzed. The results show that the tensile properties of TC11 titanium alloy are slightly affected when temperature is lower than 550℃, and on which fractures there are fiber zone and shear lip zone instead of radial zone. When temperature is beyond 550℃, the tensile elongation of TC11 titanium alloy decrease rapidly, and on which fracture there is no fiber zone but only radial zone and shear lip zone. The radial lines converge to a pot adjacent sample surface. Mixed morphology characteristics of ductile ripple, quasi-cleavage and separation along phases and grains were found on radial zone instead of the isometric ductile ripple on fiber zone. Furthermore, quasi-cleavage and cleavage morphology were observed on shear lip zone. The fracture of TC11 titanium alloy after different high temperature exposure resulted from the notch effect of oxygen contamination layer, the precipitation of α_2(Ti_3Al) and the growth of secondary α and β.