中文摘要：

为了提高TA2钛合金的耐磨性和耐蚀性，采用激光相变硬化-气体渗氮工艺对TA2钛进行表面改性。利用体视光学显微镜、透射电镜和X射线衍射仪对TA2激光相变硬化-气体渗氮层进行表面形貌、微观组织和相组成分析；利用显微硬度计对两种复合改性层的显微硬度进行测试。结果表明：TA2钛表面经激光相变硬化后，可实现430℃低温渗氮。此条件下晶粒得到细化，亚结构和缺陷密度的增加有利于氮元素和晶内扩散，相变组织与氮势梯度具有良好的对应关系。通过改善渗层的组织结构和化学成分分布状态，获得了性能优良的TA2钛表面硬化层。

英文摘要：

To improve the abrasion resistance and corrosion resistance of TA2 titanium, a laser transformation hardening-gas nitriding process was adopted to carry out the surface modification. Analysis was made for the surface morphology, microstructure and phase constitution of TA2 laser transformation hardening-gas nitrided layer by OM, TEM and XRD;and microhardness tester was used to test the microhardness of the two composite modified surfaces. The results indicate that after undergoing laser transformation hardening, the surface of TA2 titanium can be nitrided at a low temperature of 430 ℃. Under this condition, the grains are refined. The increase in sub-structure and defect density is more conducive to the intragranular diffusion of nitrogen, and there is a good correspondence between the phase transformation structure and nitrogen potential gradient. TA2 titanium surface-hardened layer with good performance is obtained through improving the structure of nitrided layer and the distribution of its chemical components.