Microstructure Evolution and Frictional Wear Behavior of Al–18Si–4Mg–2Mn–0.5Fe–xCu Alloys Fabricated by Laser Additive Manufacturing

The microstructure evolution, corrosion resistance, and wear resistance of Al–18Si–4 Mg–2Mn–0.5Fe–xCu (x = 0,1,2,3,4,5 wt%) alloys prepared by laser additive manufacturing (LAM) process are studied. It is found that the addition of Cu not only produces Cu‐rich strengthened phase, but also promotes the precipitation of the second phase. With the addition of Cu, the corrosion resistance of the alloy decreases, which is due to the increase of potential difference caused by the increase of the strengthening phase. The addition of Cu can effectively inhibit corrosion cracking. The hardness and wear resistance of the alloy increase with the increase of Cu content under the synergistic strengthening of the Q‐Al₅Cu₂Mg₈Si₆ phase and Al₂Cu phase. When the Cu content is 3 wt%, the hardness and wear resistance of the alloy are the best. However, with the increase of Cu content, part of the Q phase is transformed into the Al₂Cu phase; this synergistic strengthening effect is weakened, and the hardness and wear resistance of the alloy are reduced, but still higher than that of the alloy without Cu addition, which indicates that the addition of Cu can effectively improve the hardness and wear resistance of the alloy.