Microstructures and High Temperature Tensile Behaviours of Laser Powder Bed Fusion Fabricated Al-Mn-Sc Alloy

The introduction of Sc/Zr inoculates to aluminium (Al) alloys for laser powder bed fusion (LPBF) provides numerous benefits, including laser processability improvement, solidification microstructure control and mechanical property enhancement. Though great efforts have been put into tailoring the microstructure and room temperature mechanical properties via process parameter optimisations, the potential roles of Sc/Zr inoculate modified Al alloys for high-temperature applications were still underexplored. In this study, the microstructural stability and the elevated temperature tensile behaviours of LPBF-processed Al-Mn-Sc alloy were systematically evaluated. The alloy demonstrated high microstructural stability after both heat treatment and high-temperature tensile testing for up to 573 K. The applied tensile testing temperature and strain rate played significant influences on the elevated temperature tensile properties and deformation behaviours. Unusual intermediate temperature embrittlement (also known as ductility dip) and yield drop behaviours were observed under certain testing temperature and strain rate regimes, and the underlying deformation mechanisms were elucidated in detail. The present study is expected to shed light on future high-performance, high-temperature Al alloy development for the LPBF process.