材料科学
层状结构
马氏体
针状的
选择性激光熔化
微观结构
极限抗拉强度
复合材料
冶金
作者
W. Xu,Milan Brandt,Shoujin Sun,Joe Elambasseril,Q. Liu,Kay Latham,Ke Xia,Ma Qian
标识
DOI:10.1016/j.actamat.2014.11.028
摘要
Novel ultrafine lamellar (α + β) microstructures comprising ultrafine (∼200–300 nm) α-laths and retained β phases were created via promoting in situ decomposition of a near α′ martensitic structure in Ti–6Al–4V additively manufactured by selective laser melting (SLM). As a consequence, the total tensile elongation to failure reached 11.4% while maintaining high yield strength above 1100 MPa, superior to both conventional SLM-fabricated Ti–6Al–4V containing non-equilibrium acicular α′ martensite and conventional mill-annealed Ti–6Al–4V. The formation and decomposition of α′ martensite in additively manufactured Ti–6Al–4V was studied via specially designed experiments including single-track deposition, multi-layer deposition and post-SLM heat treatment. The essential SLM additive manufacturing conditions for Ti–6Al–4V including layer thickness, focal offset distance and energy density, under which a near α′ martensitic structure forms in each layer and then in situ transforms into ultrafine lamellar (α + β) structures, were determined. This is the first fundamental effort that has realized complete in situ martensite decomposition in SLM-fabricated Ti–6Al–4V for outstanding mechanical properties.
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