Wire arc additive manufacturing of a heat-resistant Al-Cu-Ag-Sc alloy:microstructures and high-temperature mechanical properties

With a high energy efficiency,low geometric limitation,and low cracking susceptivity to cracks,wire arc additive manufactur-ing(WAAM)has become an ideal substitute for casting in the manufacturing of load-bearing high strength aluminum components in aerospace industry.Recently,in scientific researches,the room temperature mechanical performance of additive manufactured high strength aluminum alloys has been continuously broken through,and proves these alloys can achieve comparable or even higher properties than the forged counterpart.Since the aluminum components for aerospace usage experience high-low temperature cycling due to the absence of at-mosphere protection,the high temperature performances of additive manufactured high strength aluminum alloys are also important.However,few research focuses on that.A special 2319AgSc with 0.4 wt.%Ag and 0.2 wt.%Sc addition designed for high temperature ap-plication is deposited successfully via cold metal transfer(CMT)based on WAAM.The microstructures and high temperature tensile proper-ties are investigated.The results show that the as-deposited 2319AgSc alloy presents an alternate distribution of columnar grains and equiaxed grains with no significant textures.Main second phases are Al2Cu and Al3Sc,while co-growth of Al2Cu and bulk Al3Sc is found on the grain boundary.During manufacturing,nanoscale Al2Cu can precipitate out from the matrix.Ag and Mg form nano-scale Ω phase on the Al2Cu precipitates.At 260℃,average yield strengths in the horizontal direction and vertical direction are 87 MPa±2 MPa,87 MPa±4 MPa,while average ultimate tensile strengths are 140 MPa±7 MPa,141 MPa±11 MPa,and average elongations are 11.0%±2.5%,13.5%±3.0%.Anisotropy in different directions is weak.