Microstructure and wear behavior of Mn-modified high-strength AlCu alloy fabricated via laser powder bed fusion

Abstract

In this work, a new Mn-modified AlCuMgSiTi alloy with a high relative density of 99.5 % was processed via laser powder bed fusion (LPBF) technology. The influence of Mn addition on the solidification microstructure was investigated through multiscale characterization methods, and the wear behavior of the modified alloy was evaluated via a ball-on-flat tribometer against 100Cr6 steel under three different loads (2.1 N, 10 N, and 24 N). The results demonstrate that the formation of bimode columnarequiaxed grains is attributed to the addition of Ti with nanosized Al₃Ti particles, whereas Mn is oversaturated and solid-solved within the matrix, with no significant Mn precipitation observed. This oversaturation increases the distortion of the Al matrix, improving the strain hardening capability and oxidation resistance of the material. As a result, the wear rates after Mn modification were reduced by 78.4 %, 66.7 %, and 56.8 % under 2.1 N, 10 N, and 24 N loads, respectively, compared with those of the LPBF AlCuMgSiTi alloy.