High Bending Strength Hypereutectic Al-22Si-0.2Fe-0.1Cu-Re Alloy Fabricated by Selective Laser Melting

The objective of the study is to investigate the corresponding microstructure and mechanical properties, especially bending strength, of the hypereutectic Al-Si alloy processed by selective laser melting (SLM). Almost dense Al-22Si-0.2Fe-0.1Cu-Re alloy is fabricated from a novel type of powder materials with optimized processing parameters. Phase analysis of such Al-22Si-0.2Fe-0.1Cu-Re alloy shows that the solubility of Si in Al matrix increases significantly. The fine microstructure can be observed, divided into three zones: fine zones, coarse zones, and heat-affected zones (HAZs). Fine zones are directly generated from the liquid phase with the characteristic of petaloid structures and bulk Al-Si eutectic. Due to the fine microstructure induced by the rapid cooling rate of SLM, the primary silicon presents a minimum average size of similar to 0.5 mu m in fine zones, significantly smaller than that in the conventional produced hypereutectic samples. Moreover, the maximum value of Vickers hardness reaches similar to 170 HV0.2, and bending strength increases to 687.70 MPa for the as-built Al-22Si-0.2Fe-0.1Cu-Re alloys parts, which is much higher than that of cast counterparts. The formation mechanism of this fine microstructure and the enhancement reasons of bending strength are also discussed.

Automated summary

The study investigates the microstructure and mechanical properties of hypereutectic Al-Si alloy processed by selective laser melting, showing significant improvements in hardness and bending strength compared to traditional production methods. The fine microstructure induced by rapid cooling rate of SLM results in smaller primary silicon sizes, leading to enhanced mechanical properties in the fabricated Al-22Si-0.2Fe-0.1Cu-Re alloy.