粉床型电子束3D打印纯钨及W-Nb合金的显微组织及开裂机制  

Microstructure and Cracking Mechanism of Pure Tungsten and W-Nb Alloys Fabricated by Selective Electron Beam Melting

作　　者：杨广宇[1] 汤慧萍[1] 王建[1] 贾文鹏[1] 贾亮[1] 刘楠[1] Yang Guangyu;Tang Huiping;Wang Jian;Jia Wenpeng;Jia Liang;Liu Nan(State Key Laboratory of Porous Metal Materials,Northwest Institute for Nonferrous Metal Research,Xi’an 710016,China)

机构地区：[1]西北有色金属研究院金属多孔材料国家重点实验室,陕西西安710016

出　　处：《稀有金属材料与工程》2021年第12期4342-4347,共6页Rare Metal Materials and Engineering

基　　金：国防基础科研核科学挑战专题项目(TZ2018006);陕西省重点研发项目(2020GY-146)。

摘　　要：采用粉床型电子束3D打印技术制备了纯钨及固溶强化型W-Nb合金,对2种钨基材料的显微组织和裂纹缺陷进行了分析。研究发现:二者均沿逐层累积的方向形成柱状晶,Nb元素的加入使柱状晶的平均尺寸由109.78μm降至25.10μm。纯钨并未发生显著的开裂现象,但是W-Nb合金内部存在沿晶界分布的微裂纹。从热应力累积和凝固过程2个方面分析了钨基材料开裂的原因,粉床型电子束3D打印过程包含了熔池的快速凝固-快速冷却-高温保温几个阶段,过程中纯钨及W-Nb合金均发生了回复与再结晶,使成形过程中累积的热应力得到一定的释放,缓解了热应力累积引起的开裂现象。W-Nb合金的开裂主要是由于凝固过程中液态金属无法短时间内在枝晶间进行充分流动补缩,形成大量沿晶界分布的纳米微缩孔,在微小的应力作用下就会造成合金沿晶界开裂。Pure tungsten and solid solution strengthened W-Nb alloy were fabricated by selective electron beam melting(SEBM).The microstructure and crack defects of two tungsten based materials were analyzed.The results show that columnar crystal structure along the building direction of SEBM forms both in the pure tungsten and W-Nb alloy.The addition of Nb reduces the average size of columnar crystals from 109.78μm to 25.10μm.No significant cracks form in the pure tungsten,but microcracks along the grain boundaries are found in W-Nb alloys.The rapid solidification,rapid cooling and holding at elevated temperature process in SEBM cause recovery and recrystallization of W and W-Nb alloys,so that the accumulated stress during the forming process is released.The cracking of W-Nb alloy is mainly formed during solidification,that is,because the liquid metal cannot feed the dendrite in a very short time durin g the solidification process,nanopores form and gather at the grain boundaries,which causes cracks along the grain boundary under the action of small stress.

关 键 词：增材制造 粉床型电子束3D打印 钨基材料 W-Nb合金 

分 类 号：TG146.411[一般工业技术—材料科学与工程]