Martensitic transformations in Ti-6Al-4V (ELI) alloy manufactured by 3D Printing
Martensitic transformations in Ti-6Al-4V (ELI) alloy manufactured by 3D Printing
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DOI：
10.1016/j.matchar.2018.09.042
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发表时间：
2018-12-01
影响因子：
4.7
通讯作者：
Ezhov, I.
中科院分区：
文献类型：
--
作者：
Kazantseva, N.;Krakhmalev, P.;Ezhov, I.
在本研究中，Ti-6Al-4V ELI 样品是使用激光烧结（LS）技术通过粉末床熔融（PBF）工艺制造的。通过透射电子显微镜、原子探针断层扫描、X射线衍射、纳米压痕和力学测试研究了微观结构、化学和相组成以及力学性能。研究发现，LS 样品的结构由两种不同的亚稳相变体组成，即六方 α' 马氏体相和少量的斜方 α'' 马氏体相。由于LS方法的高冷却速率，形成了马氏体α'相。在合金的显微组织中观察到{10(1)over bar2}六方马氏体拉伸孪晶。通过透射电子显微镜识别出具有内部孪晶马氏体板的小区域，这是钛合金中亚稳态斜方马氏体相的典型特征。原子探针断层扫描（APT）证实了β稳定元素在界面处的定位，可能是在孪晶或片层边界处。通过制造过程中的原位热处理，讨论了 3D 打印 Ti-6Al-4V 合金中马氏体相的结构和来源。
In the present investigation, Ti-6Al-4V ELI samples were manufactured by the powder-bed fusion (PBF) process using the laser sintering (LS) technology. Microstructure, chemical and phase constitution, and mechanical properties were studied by means of the transmission electron microscopy, atom probe tomography, X-ray diffraction, nanoindentation and mechanical testing. It was found that the structure of LS samples consisted of two different variants of metastable phases, namely the hexagonal alpha' martensitic phase and small amounts of the orthorhombic alpha '' martensitic phase. The martensitic alpha'-phase was formed because of the high cooling rates of the LS method, The {10 (1) over bar2} hexagonal martensite tensile twins were observed in the microstructure of the as-build alloy. Small areas with inner twinning martensitic plates, which are typical for the metastable orthor-hombic martensitic phase in titanium alloys, were identified by the transmission electron microscopy. Atom probe tomography (APT) confirmed localization of beta-stabilizing elements at interfaces, presumably at the twin or lamella boundaries. The structure and origin of the martensitic phases in 3D printed Ti-6Al-4V alloys are discussed with respect to in-situ heat treatment during manufacturing.