激光熔敷Ti5Si3/NiTi金属间化合物复合材料涂层组织与高温抗氧化性能研究

以Ti—Si—Ni混合合金粉末为原料,利用激光熔敷技术,在高温、高强钛合金BT9表面制得了以金属间化合物Ti5Si3为强化相、以金属间化合物NiTi为基体的金属间化合物快速凝固高温抗氧化复合材料涂层。在1000℃恒温氧化50小时的试验条件下测试了涂层的抗氧化性及氧化动力学曲线,分析了复合材料涂层及氧化膜的显微组织结构及相组成。

Microstructure and Oxidation Resistance of a Laser Clad Ti5Si3/NiTi Intermetallic Composite Coating

An oxidation resistant Ti5Si3/NiTi intermetallic matrix composite coating was fabricated on substrate of a titanium alloy BT9 by laser cladding using the Ni - Ti-Si alloy powders. The oxidation resistance of the laser clad intermetallic composide coating was investigated under the testing condition of 1000℃ and 50 hours. The results indicate that the laser clad intermetallic composite coating has a rapidly solidified homogeneous microstruc-ture consisting of Ti5Si3 primary particles uniformly distributed in the Ti5Si3/NiTi eutectic matrix and it is metal-lurgically bonded to the titanium substrate. The isothermal elevated -temperature oxidation resistance of the laser clad intermetallic composite coating is enhanced significantly. Oxidation resistance of the laser clad intermetallic composite coating was up to 1. 79 times higher than that of the original titanium alloy BT9. The oxidation kinetics of the laser clad γ/NiTi intermetallic composite coating is conforming to the parabolic-rate law equation at the testing condition.The excellent oxidation resistance of the coating is mainly attributed tO that the relatively continuous OXide scales which mainly consist of TiO2，A1203 and SiO2 prevented the inner part of the laser clad interm etallic composite coating from being further oxidized．