Influence of laser powder bed fusion of high-entropy alloy transition layer on the wetting and spreading behaviour of Al alloy on steel substrate surface

The high-quality joining of Al alloys to steel is widely used in automotive manufacturing. However, because of the significant differences in their thermophysical properties, the wetting of Al alloys on steel is very limited, which affects the joining quality. To address this challenge, the laser powder bed fusion (LPBF) technique was used to prepare an FeCoNiCrMn high entropy alloy (HEA) with a dense transition layer (DTL) and micropillar transition layer (MTL) on a steel substrate for the first time. Then, the dynamic wetting and spreading behaviours of Al-12Si alloy over the transition layer-free, DTL, and MTL steels were comparatively studied. The spreading mechanisms were revealed by the spreading dynamics and an analysis of the interfacial microstructure. This study investigated a new method to improve the wetting of Al alloys on steel substrates and elucidated the mechanism of the effect of the HEA transition layer formed using LPBF on Al/steel wetting, which may provide some guidance for improving brazing, welding, coating, and other processes involving solid/liquid interfacial interactions.