Microstructure and mechanical properties of Cu-modified AlSi10Mg fabricated by Laser-Powder Bed Fusion

Abstract

This influence of surface modification of powder feedstocks for additive manufacturing is assessed. Commercial AlSi10Mg powder was coated with 1 wt% copper using a copper formate precursor, which was reduced to metallic copper after vacuum heat treatment. Consolidated samples were produced using Laser-Powder Bed Fusion (L-PBF). Both the untreated and coated powders produced materials which exhibited high preferential crystal orientation, with grains aligned parallel to the build direction. The microstructure of the consolidated materials was characterized by SEM and TEM. The cells consisted of a α-Al matrix with copper particles decorating the intercellular region and eutectic silicon homogeneously dispersed in the cell boundary. The effect of the T6 heat treatment on the mechanical properties of the L-PBF-processed materials was a decrease in the strength. The specimens fabricated from coated powder exhibited an increased ultimate tensile strength (461 ± 0.2 MPa) and 12% elongation at break compared to the AlSi10Mg parts (346 ± 1.0 MPa) and 10% elongation. The study establishes the feasibility of modifying the composition of L-PBF-processed materials via the coating of powder feedstocks and that the coating additions can be exploited to enhance mechanical properties of parts after heat treatment.