Morphology and size effects on densification and mechanical behavior of sintered powders from Al-Si and Al-Cu casting alloys

The aim of this investigation is focused on the evaluation of the effect of two distinctive sizes and morphologies of powder particles from the recycled as-cast Al-Si and Al-Cu alloys. Elemental powders from Al-9Si, Al-5Cu alloys and a mixture 1:1 weight ratio between aforementioned casting alloys to constitute alloy powder composites are used. It is found that the sintered densification of coarser powders provides slight higher densification than finer particles. It is also confirmed a strength anisotropic effect when the tensile and compressive are evaluated. Tensile strength reveals that finer particles provide better mechanical behavior. It is clearly evidenced that the solute content affects the compressive strengths, which favors the Al-5Cu alloy powder composite (similar to 140 MPa). The lowest compressive behavior is that of the Al-9Si sample (similar to 105 MPa), and the intermediate is that of the Al4.5Si-2.5Cu composite (similar to 120 MPa). These results are intimately associated with the formed clusters of brittle Si particles inducing to microcracks at the Al-9Si alloy composite. Additionally, the specific strengths of the examined composites are determined, and the Al-5Cu composite demonstrates interesting economical and environmental-friendly characteristics. (C) 2019 Elsevier B.V. All rights reserved.