Tailoring precipitation of directed energy deposited Al-Cu alloy via laser shock peening

Abstract

Wire-arc directed energy deposition (DED) has become a promising method to fabricate large-sized metallic components. The mechanical properties of the directed energy deposited Al-Cu alloy usually can be improved by fine precipitates formed during subsequent heat treatment. In this study, a novel hybrid post-treatment method (HPTM) with laser shock peening (LSP) introduced between heat treatment was proposed. The results indicate that the yield and tensile strength of Al-Cu alloy treated by the HPTM were 38% and 13%, respectively, higher than those of the T6 counterparts. Based on the atomic scale characterization of spherical aberration transmission electron microscopy, the influencing mechanism of LSP on the precipitation process was investigated. The quantification of various strengthening mechanisms shows that the improvement of precipitation strengthening is the main reason for the excellent strength. This HPTM route provides a promising way for the post-treatment of complex additively manufactured precipitation strengthening alloy components.