高温氧化后Ti6Al4V合金渗氧层的微观结构和力学性能

Microstructure and Mechanical Properties of Oxygen-Diffusion Layer on Ti6Al4V Alloy after High-Temperature Oxidation

在850℃对Ti6Al4V(TC4)钛合金板分别进行12,24,36,48h的氧化处理,研究了高温氧化处理后合金近表面渗氧层的微观结构和力学性能。结果表明:高温氧化后的钛合金板表面出现了渗氧层,它是由间隙氧原子的固溶形成的,渗氧层中的氧含量呈梯度分布;随着深度增加,渗氧层的纳米硬度、弹性模量和残余拉应力逐渐下降;氧原子固溶于基体中引起了晶格常数的变化,这是导致梯度结构形成且力学性能提高的主要原因;残余应力的变化是氧化过程中的氧扩散和空冷过程中的热应力共同作用的结果。

Ti6A14V （TC4） alloy plate was oxidized at 850 ℃ for 12, 24, 36, 48 h, respectively, and the microstructure and mechanical properties of oxygen-diffusion layer after high-temperature oxidation were studied. Results show that a surface layer with gradient structure can be formed, and the forming of the layer was due to the solution of the interstitial oxygen atoms after oxidation treatment. The nano hardness value, elasticity modulus as well as residual stress decreased gradually with the increase of depth. The main reason for forming gradient structure and improvement of mechanical properties was attributed to dissolution of oxygen atoms, which leads to the changes of lattice parameters. Oxygen diffusion during oxidation treatment and thermal stress during air-cooling process both lead to the changes of residual stress.