TA2表面激光气体氮化组织结构和耐蚀性研究

Study on Structure and Corrosion Resistance of the TA2 Surface of Laser Gas Nitriding

采用DL-HL-T型5 kW CO2快速横流激光器对TA2钛合金进行了激光气体氮化处理。利用体视显微镜、扫描电子显微镜、X射线衍射和能谱分析对TA2激光气体氮化层进行表面形貌、微观组织和相组成的分析;利用显微硬度计和纳米力学探针对氮化区域的显微硬度及氮化层硬度的均匀性进行了测试;利用M283恒电位仪与M352测试分析软件对氮化层进行耐蚀性测试与分析。研究结果表明,经过激光表面氮化处理,在TA2表面生成了以TiN为增强相的氮化区域。该区域由氮化层、热影响区和基体3部分构成,氮化层组织主要由TiN和α-′Ti组成,厚大约30μm,硬度比较均匀;热影响区主要由细小的针状α-′Ti构成。TA2激光气体氮化提高了基体的耐均匀腐蚀和局部腐蚀的性能。

The laser gas nitriding is carried out on the surface of TA2 titanium alloy by use of the DL-HL-T 5kW continuous wave CO2 laser equipment.The stereo microscope,scanning electron microscopy,X-ray diffraction and energy spectrum analysis are adopted to analyze the surface morphology,microstructure and phase composition.The microhardness and uniformity of the hardness of the nitrided layers are measured by the microhardness tester and the nano indenter.The corrosion resistance of nitrided layers is analyzed by M283 potentiostat and M352 analyse software.The result shows that TiN is formed on the surface of TA2 which serves as a reinforcing phase.It is made up of nitrided layer,heat affected zone and the base metal after the laser gas nitriding treatment.The nitrided layer mainly consists of TiN and α′-Ti which has a uniform hardness with a thickness of 30 μm.The heat affected zone is mainly composed of needle α′-Ti.TA2 laser gas nitriding improves the uniform and localized corrosive resistance of the base metal.