Effect of the Deposition Process on High-Temperature Microstructure and Properties of the Direct Energy Deposition Al-Cu Alloy

Abstract

The excellent microstructure and mechanical properties of Al-Cu alloy deposited using the Direct Energy Deposition (DED) process has been shown in previous studies, which is the most likely aluminum alloy material to meet the load-bearing requirements of hypersonic aircraft. However, its high-temperature performance and the law of microstructure transformation during the high-temperature process still need to be determined. In this paper, DED Al-Cu alloy samples were prepared using the Cold Metal Transfer (CMT) process, CMT Pulse process, and CMT Pulse Advanced process. The effect of different deposition processes on the microstructure and mechanical properties of the deposits was investigated at 200 °C for 30 min. The results show that the Al-Cu alloy’s main strengthening phase θ′ is excessively transformed into the equilibrium θ phase after the high-temperature process, which is the main reason for the degradation in the DED Al-Cu alloy’s properties at high temperatures. Different deposition processes have almost no effect on the high-temperature performance of the DED Al-Cu alloy, and the deposition process can be selected according to the product’s structure.