激光熔化沉积Ti60合金、TiCp/Ti60复合材料的高温拉伸持久寿命及断裂过程

通过激光熔化沉积工艺制备出Ti60合金和质量分数为5%的TiCp/Ti60复合材料，分析比较了两种材料的微观组织及高温(600 ℃)拉伸持久性能。结果表明，所沉积TiCp/Ti60复合材料中初生TiC呈树枝晶分布于原始β晶界，共晶TiC呈颗粒状分布于α -Ti板条间，TiC的存在导致基体组织细化。TiCp/Ti60复合材料较基体合金具有更加优异的高温(600 ℃)拉伸持久寿命，其高温拉伸持久断裂过程为：增强体与基体界面脱粘、α -Ti/β -Ti的界面处微孔形核、长大、横向扩展及连接，最终导致复合材料的失效。

High-Temperature Tensile Rupture Life and Fracture Procedure of Laser Direct Deposited Ti60 Alloy and TiCp/Ti60 Composites

Ti60 alloy and TiCp (mass fraction of 5%)/Ti60 titanium matrix composites are fabricated by laser direct deposition process. The microstructure and tensile rupture life under 600 ℃ are investigated and compared. The results indicate that, for laser direct deposited TiCp/Ti60 composites, primary TiC appears as dendrites and distributes at the original β grain boundary, and the eutectic TiC appears as particulate and distributes between α laths. The existence of TiC results in refinement of the matrix. Compared with the Ti60 alloy, TiCp/Ti60 composite exhibits a superior rupture life and creep resistance under 600 ℃. The creep rupture of the composite is primarily initiated by a mixture of interface debonding between TiC and the matrix and interface voiding between α-Ti and β-Ti, which is followed by the ductile failure through the matrix.