Heat treatment of Al-Cu-Li-Sc-Zr alloy produced by laser powder bed fusion

Abstract

Developing effective heat treatments to enhance the property of LPBF-produced aluminum alloys has received strong attention in recent years. In this paper, we present a systematic study on the effect of heat treatment on the LPBF-fabricated Al-Cu-Li-Sc-Zr alloy. The heat treatment temperatures were designed according to the phase transformation and precipitation kinetic analyses. Based on precipitation kinetic analysis, the heat treatment durations of LPBF-fabricated Al-Cu-Li-Sc-Zr alloy were designed shorter than those of conventional manufacturing. Aging at 170 °C caused a small amount of T 1 phases to precipitate, and thus slightly increased the yield strength (YS) of the samples. Aging at 300 °C caused plenty of Al 3 (Sc, Zr) phases to precipitate, and thus significantly raised the YS of the samples. Solid solution treatment at 520 °C caused grain coarsening and coarse AlCuSc phases precipitated, and thus decreased the tensile properties. The solid solution treatment is not suitable for LPBF-fabricated Al-Cu-Li-Sc-Zr alloy. This study provides a systematic understanding of post heat treatment on microstructure and mechanical properties of LPBF-fabricated Al-Cu-Li-Sc-Zr alloy, contributing to heat-treatable Al Li alloys design for LPBF. • The heat treatment temperatures and durations of LPBF-fabricated Al-Cu-Li-Sc-Zr alloy were designed according to phase transformation analysis and precipitation kinetic analysis. • The precipitation of a small amount of T 1 phases after aging at 170 °C causes a slight rise in YS. • The precipitation of numerous Al 3 (Sc, Zr) phases after aging at 300 °C results in more than 100 MPa higher increase of YS. • Tensile properties deteriorate as a result of grain coarsening and precipitation of coarse insoluble phases after solutionizing at 520 °C.