Microstructural engineering of a dual-phase Ti-Al-V-Fe alloy via in situ alloying during laser powder bed fusion

作者：Ming Chen, S. Van Petegem, Zhiyi Zou, Marco Simonelli, Y. Y. Tse, Cynthia Sin Ting Chang, Małgorzata G. Makowska, Darío Ferreira Sánchez, Helena Moens-Van Swygenhoven · 发表于：Additive manufacturing · 年份：2022 · DOI：10.1016/j.addma.2022.103173 · 被引用次数：76 · 研究领域：Additive Manufacturing Materials and Processes、High Entropy Alloys Studies、Titanium Alloys Microstructure and Properties

When Ti-6Al-4V is processed by laser powder bed fusion (L-PBF), acicular martensitic α’-Ti grains are formed within the columnar prior β-Ti grains, resulting in inferior mechanical properties. The application of blended powders in L-PBF enables to tailor the microstructures and obtain a mixture of α’ + β phases. In this work, we demonstrate an effective method to engineer the phase fraction of an L-PBF manufactured Ti alloy using blended powders consisting of Ti-6Al-4V and 3 wt% Fe particles. By varying laser parameters, the as-built microstructures transit from α’ dominated microstructure to a nearly complete β-dominant microstructure. High-speed operando X-ray diffraction during L-PBF processing combined with X-ray fluorescence and EBSD characterization allows for relating microstructure to the spatial distribution of the β-stabilizer Fe under the high cooling rates typical for L-PBF. The as-built microstructure containing large amounts of β phase achieves high strength and enhanced ductility without post-processing heat treatments.