High temperature mechanical properties of wire-arc directed energy deposited Al-Ce-Mg alloy

Abstract

The Al-15Ce-3Mg (wt.%) alloy was fabricated by wire-arc based directed energy deposition (WA-DED), and its high temperature mechanical properties were investigated to facilitate the development of Al-Ce-Mg alloys. The WA-DED Al-15Ce-3Mg alloy forms hypereutectic microstructure, which mainly includes large primary Al₁₁Ce₃ intermetallics and fine Al₁₁Ce₃/α-Al eutectics. The WA-DED Al-15Ce-3Mg alloy has high strength and good plastic deformation ability at high temperatures, under the combined effects of precipitation strengthening and solid solution strengthening. Its tensile strength can reach 86~132 MPa at 220~300 ℃, which is similar to that of LPBF-formed and HIP-treated Al-15Ce-9Mg alloy. While the elongation of WA-DED Al-15Ce-3Mg is significantly higher, reaching 12.9%~29%. Significant strain softening occurs during the tensile process due to matrix softening at elevated temperatures. Moreover, WA-DED Al-15Ce-3Mg alloy also shows good high temperature compressive strength, which is 360 MPa at 220 ℃, 310 MPa at 250 ℃ and 240 MPa at 300 ℃ at the compressive strain of 30%. For the high temperature creep properties, WA-DED Al-15Ce-3Mg alloy displays higher creep resistance compared to Al-3Mg alloy at similar temperature, and its creep strain accumulates faster as the temperature and stress increase. The dislocation creep are the main creep deformation mechanisms at 220 ℃, 250 ℃ and 300 ℃. The dislocation climb controlled by lattice self-diffusion dominates creep deformation at 220 ℃ and 250 ℃, while the dislocation glide is the controlling mechanism for creep at 300 ℃. This study demonstrates that WA-DED is an attractive method for fabricating Al-Ce-Mg alloys with a good combination of strength and ductility.