Si元素对Ti-6Al-2Zr-1Mo-1V钛合金力学性能的影响

Effect of Silicon on Mechanical Properties of Ti-6Al-2Zr-1Mo-1V Alloy

摘要:

本文研究了Si元素含量对Ti-6Al-2Zr-1Mo-1V钛合金在室温和500℃力学性能的影响。采用扫描电镜（SEM）和透射电镜（TEM）对断口形貌和微观结构进行了分析，硅化物的形核和生长与力学关系密切。结果表明：在Ti-6Al-2Zr-1Mo-1V合金中加入0.04wt%～0.14wt%的Si可以提高合金的抗拉强度和高温持久性能，塑性几乎不变，冲击韧性和平面应变断裂韧度显著降低。Si的加入使合金呈现由韧性向脆性断裂转变的趋势，放射区增大纤维区和剪切唇区减小。当Si含量小于0.09wt%时，Si元素完全溶解于α和β相中，以固溶强化机制为主。当Si元素含量达到0.14%时， 相界处析出硅化物，强化机制包括固溶强化和析出强化。

Abstract:

The influence of Si content on mechanical properties of Ti-6Al-2Zr-1Mo-1V titanium alloy at room temperature and 500℃ was studied. The fracture morphologies and microstructures were analyzed by scanning electron microscope (SEM) and transition electronic microscope (TEM). The nucleation and growth of silicide were related to the mechanical properties. It was shown that the tensile strength and high-temperature enhance performance were improved when Si was added from 0.04wt% to 0.14wt% in the Ti-6Al-2Zr-1Mo-1V alloy; the ductility is almost unchanged; impact toughness and plane strain fracture toughness were decreased. The alternation tendency from ductility to brittle fracture can be found with the addition of Si, the radial region enlarged, and the area of fibrous region and shear lip minified. When the content of Si is less than 0.09wt%, the Si elements are dissolved in α and β phase and increase strength, solid solution strengthen mechanism is the main mechanism. On the other hand, the silicide precipices along phase boundary when the content of Si reaches 0.14%wt, which led a combined strengthening by solution and precipitation.