Advances in additively manufactured titanium alloys by powder bed fusion and directed energy deposition:Microstructure,defects,and mechanical behavior

Ti and its alloys have been broadly adopted across various industries owing to their outstanding proper-ties,such as high strength-to-weight ratio,excellent fatigue performance,exceptional corrosion resistance and so on.Additive manufacturing(AM)is a complement to,rather than a replacement for,traditional manufacturing processes.It enhances flexibility in fabricating complex components and resolves machin-ing challenges,resulting in reduced lead times for custom designs.However,owing to distinctions among various AM technologies,Ti alloys fabricated by different AM methods usually present differences in mi-crostructure and defects,which can significantly influence the mechanical performance of built parts.Therefore,having an in-depth knowledge of the scientific aspects of fabrication and material properties is crucial to achieving high-performance Ti alloys through different AM methods.This article reviews the mechanical properties of Ti alloys fabricated by two mainstream powder-type AM techniques:powder bed fusion(PBF)and directed energy deposition(DED).The review examines several key aspects,en-compassing phase formation,grain size and morphology,and defects,and provides an in-depth analysis of their influence on the mechanical behaviors of Ti alloys.This review can aid researchers and engi-neers in selecting appropriate PBF or DED methods and optimizing their process parameters to fabricate high-performance Ti alloys for a wide range of industrial applications.