The study investigated the impact of heat treatment on the microstructure and tensile properties of GH4061 alloys fabricated by selective laser melting.Findings demonstrated that the as-built columnar grains experienced epitaxial growth spanning multiple molten pools,resulting in the formation of cellular substructures.Following heat treatment,as the solid solution temperature increased,there was a gradual shift in grain orientation towards the(101)and(111)crystal planes.The Laves phase transitioned from elongated chains to granular forms and dissolved at approximately 1060℃.The δ phases that precipitated at grain boundaries transformed from coarse bulk structures to disc-shaped,and eventually to short rod-shaped configurations.The average sizes of γ′ and γ″ phases are 23.53 nm,24.43 nm,25.34 nm and 25.66 nm at solution temperature of 980℃,1020℃,1060℃,1100℃,respectively.The mechanical properties of the alloys after heat treatment show significant improvement at both room temperature and 650℃.Specifically,the tensile strengths at room temperature and 650℃for the sample subjected to the 980℃solid solution aging heat treatment are 1342 MPa and 1120 MPa,respectively.As the solid solution temperature increases,the room temperature tensile strength at 1020℃,1060℃and 1100℃decreases by approximately 6.4%,8.3%,and 10%than that at 980℃,respectively.At 650℃,the tensile strength at 1020℃,1060℃and 1100℃decreases by approximately 7.9%,8.8%,and 11%than that at 980℃,respectively,while the plasticity increases.
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