Improving the wear resistance of 50 wt% Si particle-reinforced Al matrix composites treated by over-modification with a Cu-P modifier

As lightweight wear-resistant structural materials, Sip/Al composites have the potential to be utilized in the automotive, aerospace, and electronics industries. However, coarsening of the Si particles occurs, thereby limiting the development of such materials. In this work, the effects of a Cu-P modifier on the microstructure and wear resistance of a 50 wt% Sip/Al composite are investigated using SEM, EBSD, TEM, nanoindentation, and reciprocating wear tests. The refining effect on Si particles in the composite is optimal when the modifier content is 3 wt%, but the wear resistance is not ideal. After over-modification, the wear performance reaches a peak with a wear rate of 3.32 × 10−7 mm2/N, realizing a reduction of 83.6 % and 21.7 % compared to the unmodified and optimal modified composites. Since the Al2Cu phase is formed in situ in the Cu-P modified composites and the strength of the Al2Cu phase is higher than that of the matrix, the performance of the over-modified composite is improved. The wear of the unmodified composite is dominated by delamination wear, accompanied by oxidation wear, adhesive wear, and abrasive wear. After modification, the composite is subject to the combined action of abrasive wear, oxidation wear, and adhesive wear. These results suggest that the over-modification of the Cu-P modifier is an effective approach to improving the wear resistance of Sip/Al composites.