Nanoprecipitates enhanced wear resistance of laser powder bed fusion-processed high-strength Al−Cu−Mg−Si−Ti alloy

Abstract

Solidification cracking during laser powder bed fusion (LPBF) and poor wear resistance of high-strength aluminum alloys hinder their application in aerospace and automotive fields. In the present work, a novel defect-free Al-Cu-Mg-Si-Ti alloy was manufactured by LPBF. The densification behavior research shows that the threshold value to manufacture the full-density Al-Cu-Mg-Si-Ti alloy by LPBF is a volumetric energy density (VED) of 141.7 J mm−3. The LPBF processed sample shows a heterogeneous microstructure consisting of ultrafine equiaxed grains and columnar grains. Dry sliding tests indicate that the wear rate of the as-built samples is 3.9 ± 0.4 × 10−5 cm3 m−1 with dominant abrasive wear under an applied load of 2.1 N. At an applied load of 24 N, the wear mechanism transforms to severe delamination and abrasion with a high wear rate of 42.1 ± 0.1 × 10−5 cm3 m−1. After the aging treatment, the size and number density of nanosized S’ and Q’ precipitated phases increase significantly, which results in an increased hardness and better wear resistance.