Selective Laser Melting Additive Manufacturing of Novel Aluminum Based Composites With Multiple Reinforcing Phases

Abstract

The selective laser melting (SLM), due to its unique additive manufacturing (AM) processing manner and laserinduced nonequilibrium rapid melting/solidification mechanism, has a promising potential in developing new metallic materials with tailored performance. In this work, SLM of the SiC/AlSi10Mg composites was performed to prepare the Albased composites with the multiple reinforcing phases. The influence of the SLM processing parameters on the constitutional phases, microstructural features, and mechanical performance (e.g., densification, microhardness, and wear property) of the SLMprocessed Albased composites was studied. The reinforcing phases in the SLMprocessed Albased composites included the unmelted micronsized SiC particles, the in situ formed micronsized Al4SiC4 strips, and the in situ produced submicron Al4SiC4 particles. As the input laser energy density increased, the extent of the in situ reaction between the SiC particles and the Al matrix increased, resulting in the larger degree of the formation of Al4SiC4 reinforcement. The densification rate of the SLMprocessed Albased composite parts increased as the applied laser energy density increased. The sufficiently high density (∼96% theoretical density (TD)) was achieved for the laser linear energy density larger than 1000 J/m. Due to the generation of the multiple reinforcing phases, the elevated mechanical properties were obtained for the SLMprocessed Albased composites, showing a high microhardness of 214 HV0.1, a considerably low coefficient of friction (COF) of 0.39, and a reduced wear rate of 1.56 أ— 10−5 mm3 N−1 m−1. At an excessive laser energy input, the grain size of the in situ formed Al4SiC4 reinforcing phase, both the stripand particlestructured Al4SiC4, increased markedly. The significant grain coarsening and the formation of the interfacial microscopic shrinkage porosity lowered the mechanical properties of the SLMprocessed Albased composites. These findings in the present work are applicable and/or transferrable to other laserbased powder processing processes, e.g., laser cladding, laser metal deposition, or laser engineered net shaping.