Laser welding of FeCoCrNiMnAl x ( x  = 0,0.75) high-entropy alloys fabricated by additive manufacturing

Abstract

In the present study, the laser melting deposition (LMD) technology was adopted to fabricate FeCoCrNiMn and FeCoCrNiMnAl_0.75 high entropy alloys (HEAs). Then, laser welding method was used to join the HEAs in forms of similar (FeCoCrNiMnAl/FeCoCrNiMnAl and FeCoCrNiMnAl0.75/FeCoCrNiMnAl0.75) and dissimilar (FeCoCrNiMnAl0/FeCoCrNiMnAl0.75) combinations, respectively. Ultra-depth field microscope and electron backscatter diffraction detection were used to observe the macro-morphology and microstructure, respectively. It was found that the width of the weld bead and heat-affected zone with higher aluminium content was larger. In both base metals and welded joints, aluminium promoted the face-centered cubic (FCC) phase transfer into body-centered cubic (BCC), significantly refined the grain and the dislocation density of HEA is also increased, which increased strength and hardness, and decreased ductility.

Highlights

The FeCoCrNiMn/FeCoCrNiMn, FeCoCrNiMn/FeCoCrNiMnAl_0.75, FeCoCrNiMnAl_0.75/FeCoCrNiMnAl_0.75 joints were produced by laser welding.

The widths of the weld bead and heat-affected zone increased with higher Al content.

The weld bead with higher content of Al exhibited higher strength and hardness, but lower ductility.