Control of Microstructure in Ti-6Al-4V Porous Structure Fabricated by Electron Beam Powder Bed Fusion

Abstract

Electron beam powder bed fusion has attracted much attention as an important technique for fabricating three-dimensional Ti- 6Al-4V structures for biomedical applications. Since long bones possess uniaxial anisotropy, three-dimensional macrostructures with unidirectionally elongated pores are promising candidates for biomaterials. The Young’s modulus of three-dimensional macrostructures with unidirectional pores is dominated by porosity and/or pore size. As a technique to further control the Young’s modulus, the combination of uniaxial anisotropy of macrostructure and microstructure is expected. In this article, the grain structure and the variants selectivity were analyzed through phase transformation using the SEM-EBSD method. The microstructure analysis demonstrates that there is no variant selectivity through phase transformation, but that electron beam scanning promotes the formation of elongated β-phase columnar grains along the building direction above the α/β transition temperature.