热处理对Ti-6Mo-5V-3Al-2Fe-2Zr合金拉伸性能的影响

研究了固溶+单级时效处理、固溶+双级时效处理、固溶+随炉冷却处理对新型亚稳β钛合金Ti-6Mo-5V-3Al-2Fe-2Zr的显微组织和拉伸性能的影响。结果表明：与固溶+单级时效处理相比，固溶+双级时效处理析出的晶内次生α相间距减小和体积分数增大而使合金的强度提高。两种热处理都使合金中生成连续的晶界α相，导致合金的塑性降低；与上述两种热处理相比，固溶+随炉冷却处理使合金中析出的晶内次生α相的间距明显减小且沿晶界生成向晶内生长的α_wgb相，使合金的强度和塑性显著提高，其抗拉强度达到1421 MPa，断后伸长率为7.7%；与次生α相的体积分数相比，其间距是影响合金强度的主要因素。随着次生α相间距的减小，合金的强度提高。

Effect of Heat Treatment on Tensile Property of Ti-6Mo-5V-3Al-2Fe-2Zr Alloy

The effect of three type of heat treatments on the microstructure and tensile properties of a novel metastable β-titanium alloy Ti-6Mo-5V-3Al-2Fe-2Zr was investigated, namely solution and single-stage aging, solution and two-stage aging, as well as solution and furnace cooling. The results show that: compared with the solution and single-stage aging treatment, the strength of the alloy was improved with the decrease of the spacing of secondary α phase precipitated within grains and the increase of its volume fraction by solution and two-stage aging treatment. Continuous α phase formed at grain boundary resulted by the above two heat treatment processes, which leading to poor plasticity of the alloy. Compared with the above two heat treatment processes, the heat treatment of solid solution and furnace cooling could induce obviously the decrease of the spacing of the intracrystalline secondary α phase precipitated, thus increase the amount of α_wgb phase formed along the grain boundary and grew into the grain, thereby increase significantly the strength and plasticity of the alloy i.e., the tensile strength of the alloy reaches 1421 MPa, and the fracture elongation is 7.7%. Relative to the volume fraction of the secondary α phase, the spacing is the main factor affecting the strength of the alloy. With the decrease of the spacing of the secondary α phase, the alloy strength increases.