Comparison study on microstructure and mechanical properties of Ti-6Al-4V alloys fabricated by powder-based selective-laser-melting and sintering methods

To better understand the structure-mechanical properties relation of additively manufactured Ti-6Al-4V (Ti64) alloys, a comparison study was performed on Ti64 alloys fabricated by powder-based selective laser melting (SLM) and sintering methods. It is found that the SLM Ti64 alloy has prior β grains filled with (lath α + needle α′) structure. While Ti64 alloys sintered over and below β → α transformation temperature have widmanstatten α + β and lamellar α + β structure, respectively. The SLM Ti64 alloy has higher strength and hardness than sintered alloys, but possesses similar Young's modulus to the spark plasma sintered alloy. The mechanisms leading to the different mechanical properties are discussed based on phase compositions and contents. The results suggest that SLM Ti64 alloys potentially have better mechanical performance compared with those fabricated by conventional sintering methods. [Display omitted] •Ti64 alloys fabricated by selective laser melting exhibit lath α and needle α′.•Ti64 sintered above and below β transformation temperature have widmanstatten and lamellar-(α+β) structure, respectively.•SLM Ti64 alloys have higher strength and hardness but similar Young’s modulus compared with SPS alloys.•High tensile strength in SLM Ti64 alloys is mainly contributed by needle α′.