Heat treatment strategies for tailoring the microstructure of aluminium matrix composites fabricated via LPBF

Bona Marco - Politecnico di Milano (Italy)

Laser Powder Bed Fusion (LPBF) technology has enabled the production of high-performance aluminium alloys tailored for advanced applications in aerial mobility. However, the distinct microstructure generated by LPBF—characterized by a fine cellular and dendritic morphology, high cooling rates, and residual stresses—differs substantially from that of traditionally cast alloys, necessitating the development of customized heat treatments. This study investigates the effects of tailored post-process heat treatments on the microstructure and mechanical properties of LPBF-fabricated aluminium matrix composites (AMCs) enhanced with inoculants, designed to improve grain refinement and overall alloy stampability.

The addition of inoculants during alloy production promotes a refined grain structure and aims to mitigate issues such as hot cracking, a common challenge in LPBF processing of high-strength aluminium alloys. Post-process heat treatments are assessed to optimize the distribution and stability of precipitates and to control grain morphology for enhanced mechanical properties. Conventional heat treatments, such as T5 and T6, have shown limited effectiveness on LPBF-produced alloys due to their unique microstructural features. Consequently, alternative thermal profiles are explored to develop treatments that better align with the specific characteristics of LPBF materials, thereby achieving improved mechanical performance.

Preliminary microstructural analyses and mechanical testing provide insights into the alloy’s response to varied heat treatment conditions, enabling the identification of optimal parameters for enhancing the material’s structural performance. Through this approach, the study aims to advance the understanding of LPBF-specific metallurgy, focusing on the interplay between inoculant-driven grain refinement and post-process thermal treatments.

These findings contribute to the field by providing an in-depth look at how different heat treatment profiles impact the properties of metal composite materials fabricated by LPBF. The study’s results help establish guidelines for thermal processing specific to 3D-printed aluminium materials, supporting the development of treatments that maximize strength and durability. Such insights are valuable for promoting the wider.