激光选区熔化颗粒增强钛基复合材料的抗压性能

Compression resistance of particle reinforced titanium matrix composites prepared by selective laser melting

采用激光选区熔化(selective laser melting,SLM)制备LaB_(6)颗粒增强钛基复合材料,研究不同激光能量密度下试样的致密化行为、显微组织、物相及其在准静态和动态冲击条件下的力学性能。结果表明:LaB_(6)颗粒的加入在一定程度上改变了材料的致密化行为,过高或者过低的激光能量密度均会降低试样的致密度。而增强颗粒的加入细化了基体材料的晶粒,钛合金的初始β晶粒及针状α晶粒的晶界有一定程度的弱化,从而导致复合材料的屈服强度和极限强度增加,但延展性降低,同时复合材料表现出明显的应变率强化效应。与SLM成型Ti-6Al-4V合金相比,复合材料在塑性段的应变硬化效应和失稳阶段的脆性断裂特征更显著,为激光增材制造高性能颗粒增强钛基复合材料的动态抗压性能优化提供理论基础。

Selective laser melting(SLM)was used to prepare LaB_(6) particle-reinforced titanium matrix composites(PRTMCs),the influence of laser energy on the densification behavior,phase,microstructure and the corresponding mechanical properties under quasi-static and impacting conditions were studied.The results show that the densification behavior of Ti-6Al-4V alloy is changed to some extent by the introduction of LaB_(6) particles,and the density of PRTMCs is reduced by either too high or too low laser energy input.Significant grain refinement happens after the addition of LaB_(6) particles,the grain boundary of the initialβand acicularαis weakened.As a consequence,the yield stress and ultimate compressive stress of the PRTMCs are enhanced but the ductility is weakened to some extent,meanwhile,PRTMCs exhibit obvious strain rate strengthening effect.Compared with the SLMed Ti-6Al-4V,the strain strengthening effect in the plastic deformation stage and brittle fracture characteristics in the instability stage of PRTMCs become more notable.Through this study,a theoretical basis for the dynamic compressive performance of laser additive manufactured PRTMCs can be provided.