激光直接沉积成形Ni3Al合金的裂纹分析  

Crack analysis of NiAl alloy formed by direct laser deposition

作　　者：岳锦涛 庞建明[1] 赵琳[1] 朱逸超 梁耀健 周上程 YUE Jintao;PANG Jianming;ZHAO Lin;ZHU Yichao;LIANG Yaojian;ZHOU Shangcheng(Central Iron and Steel Research Institute Group,Beijing 100081;Beijing Institute of Technology,Beijing 100081)

机构地区：[1]钢铁研究总院,北京100081 [2]北京理工大学,北京100081

出　　处：《粉末冶金工业》2021年第2期57-62,共6页Powder Metallurgy Industry

基　　金：国家重点研发计划资助项目(2020YFE0200900)。

摘　　要：激光直接沉积成形技术给Ni3Al合金提供了更广泛的应用场景,但成形过程中的热裂倾向限制了其应用。对Ni3Al合金激光直接沉积成形热裂问题展开研究和讨论,通过微观表征及力学性能测试探究了裂纹形成机制,并提出了相应的成形工艺优化方案。结果表明:Ni3Al合金在激光直接沉积成形时,会产生明显的宏、微观沿晶裂纹。枝晶偏析使得晶界上Ti、Al富集,促进了γ/γ?共晶相的形成,弱化了晶界,在快速热循环带来的残余应力不断积累下,裂纹发生沿晶扩展。通过优化激光工艺合理降低激光线能量密度,改善成形气氛,可以有效克服Ni3Al合金激光直接沉积成形的热裂倾向,实现构件的无裂纹增材制造。Direct laser deposition forming technology provides wider application scenarios for Ni3Al alloys, but the tendency of thermal cracking during forming limits its application. The hot cracking problem of Ni3Al alloy laser direct deposition forming has been studied and discussed, the crack formation mechanism is explored through micro characterization and mechanical property test, and the solution to optimize process optimization is proposed.The results show that Ni3Al alloy has obvious thermal cracking tendency during laser direct deposition forming,and macro and micro intergranular cracks will occur. The enrichment of Ti and Al elements at grain boundaries caused by dendrite segregation promotes the formation of γ/γ′ eutectic phase, which weakens grain boundary. In the process of rapid thermal cycling, the accumulation of residual stress causes the crack to propagate along the grain boundary. By improving the forming atmosphere and optimizing the laser process to reasonably reduce the energy density of the laser line, the thermal cracking tendency of direct laser deposition forming of Ni3Al alloy can be effectively overcome, and the crack-free additive manufacturing of components can be realized.

关 键 词：NI3AL 激光直接沉积成形 激光能量线密度 裂纹分析 工艺优化 

分 类 号：TG174.4[金属学及工艺—金属表面处理] TG665[金属学及工艺—金属学]