Effect of hot isostatic pressing (HIP) on Al composite parts made from laser consolidated Al/Fe2O3 powder mixtures

Selective laser melting (SLM) was used to manufacture Al composite parts from Al/5–15 wt%Fe2O3 powder mixtures and followed by hot isostatic pressing (HIP) post-treatment, in order to assess the influence of HIP on density, hardness and microstructure. It was found that the HIP post-treatment slightly increased the density, but it failed to efficiently densify the material due to formation of thick oxide bands between solids within SLM process, expanding with increasing the iron oxide. The hardness also decreased after HIP, attributed to high temperature annealing impact of HIP post-treatment on microstructure (such as coarsening, coalescence and transformation of phases). The microstructural phases before HIP were a combination of equilibrium and stable phases (i.e. Al13Fe4 and α-Al2O3) plus phases such as Al2Fe, AlFe, Fe3Al, and intermediate-Al2O3 (formed in high Fe2O3 contents), but only equilibrium and stable phases remained after HIP post-treatment.

► HIP post-treatment is carried out on laser consolidated Al/Fe2O3 powder mixtures.
► HIP post-treatment fails to achieve a dense material.
► Hardness decreases after HIP.
► Coarsening and coalescence are the main effects of HIP on microstructure.
► HIP converts intermediate combinations to equilibrium and stable phases.