Influence of the MEA Content on the Microstructure and Mechanical Properties of Ti-MEA Alloy Fabricated by Laser Additive Manufacturing

Author of the article:HE Qiuju1, CHENG Yao1,2, HUANG Xinde1, LUO Xuan1

Author's Workplace：1.Key Laboratory for Lightweight Materials, Nanjing Tech University, Nanjing 210009, China; 2. Materials Academy, JITRI, Suzhou 215132, China

Key Words： Ti-MEA alloy; selective laser melting; microstructure; mechanical properties; grain refinement

Abstract：Puretitanium is widely used in many fields but suffers from insufficient hardness and wear resistance. Ti-xMEA alloys with different CoCrNi medium-entropy alloy (MEA) contents (0.5 wt.%, 1 wt.%, and 2 wt.%) were prepared by selective laser melting to investigate the effects of the MEA content on their microstructures and mechanical properties. The results show that after MEA is added, the alloy forms a composite structure of α martensite and Ni2Ti precipitated phases, the prior β grains transform from columnar grains to equiaxed grains, and the α martensite is significantly refined. With increasing MEA content, the strength of the alloy increases continuously. In particular, compared with that of pure Ti, the yield strength of the Ti-2MEA alloy increases from 484 MPa to 624 MPa, and the ultimate tensile strength increases from 585 MPa to 765 MPa, whereas the elongation remains at 13.3%, indicating better synergy between strength and plasticity. The synergistic effect of grain refinement strengthening, solid solution strengthening and Ni2Ti precipitation strengthening is the main mechanism underlying the improvement in the properties of the alloy.