Laser powder bed fusion of a non-equiatomic FeNiCoAl-based high-entropy alloy: Printability, microstructure, and mechanical properties

Abstract

In this work, the laser powder bed fusion (LPBF) process has been applied to fabricate the FeCoNiAlTaB (NCATB) high entropy alloys. The influence of process parameters including laser power and scanning speed on the relative density and microstructure were investigated. A sample with relative density of 99.8% can be achieved by optimal process parameters with laser power of 120 W and scanning speed of 800 mm/s. It can be found that the NCATB alloy maintains the FCC single-phase structure at different parameters, which is consistent with the pre-alloyed powder. According to the tensile test results, samples fabricated with different direction show similarity in strength and anisotropy in plasticity. Therefore, the causes of mechanical property anisotropy are discussed in terms of strengthening mechanism, texture and defects, separately. Compare to the as-cast samples, the printed samples show a substantial improvement in mechanical properties, which was contribute to the grain refinement, fine cellular morphology and high dislocation density.