Abstract
The selective laser melting(SLM)with subsequent cold rolling and annealing is used to produce high-density lattice defects and grain refinement in the CoCrNi medium-entropy alloys(MEAs).The superior comprehensive mechanical properties have been achieved in the as-SLMed CoCrNi alloy after rolling and annealing.The as-SLMed alloys delivered the yield strength of 693.4 MPa,the ultimate tensile strength of 912.7 MPa and the fracture strain of 54.4％.After rolling with 70％reduction in thickness and annealing at 700℃for 2 h.the yield strength,ultimate tensile strength and fracture strain reached 1161.6 MPa,1390.8 MPa and 31.5％,respectively.The exceptional strength-ductility synergy is mainly attributed to the refined hierarchical microstructures with coarsening grains at a level of 30 pm and ultrafine grains at a level of 1 pm,and the heritage of dislocation-formed sub-grains and other lattice defects.This investi-gation demonstrates that the SLM with subsequent rolling and annealing is beneficial to fabricate high strength and ductile MEAs with single face-centered cubic(fcc)structure.
基金项目
国家重点研发计划(2020YFB0311300ZL)
国家自然科学基金(52071343)
NETL
NSTL
维普
万方数据