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 beta grains filled with (lath alpha + needle alpha') structure. While Ti64 alloys sintered over and below beta -> alpha transformation temperature have widmanstatten alpha + beta and lamellar alpha + beta 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.