Preparation of a Ti–Al–Si based intermetallic alloy from Ti6Al4V and AlSi10Mg powders by laser powder bed fusion and hot isostatic pressing

Abstract

A Ti–44Al–1.7V–0.2Mg–4.5Si (at%) alloy was successfully fabricated via laser powder bed fusion (LPBF) using a blend of Ti6Al4V and AlSi10Mg powders. Optimized process parameters, including low laser power (80–100 W), a hatch spacing of ∼0.12 mm, and high scan speeds (∼1400 mm s⁻¹), were critical for achieving the desired dimensions and quality. Despite optimization, the microstructure revealed defects such as cracks, pores, and unmelted Ti-based particles. Subsequent hot isostatic pressing (HIP) reduced these defects by up to 90% and improved microstructural homogeneity by eliminating unmelted particles. Heat treatment (HT) further refined the structure, producing a multiphase composition dominated by γ-TiAl, α₂-Ti₃Al and Ti₅Si₃ precipitates. Mechanical testing revealed anisotropic behaviour, with hardness, compressive yield strength, and plastic deformation at room temperature (RT) higher in the direction perpendicular to the build direction. The alloy demonstrated excellent high-temperature resistance, achieving a maximum compressive strength of ∼1000 MPa at RT, 490 MPa at 850 °C, and 350 MPa at 900 °C. This study presents a novel LPBF-based method for fabricating TiAl-based alloys, combining HIP and HT to enhance microstructural quality and mechanical performance, paving the way for advanced high-temperature applications.