Structural effect of low Al content in the in-situ additive manufactured CrFeCoNiAlx high-entropy alloy

The current work considers the effect of the low Al fraction (x = 0.01, 0.05, and 0.1) on the microstructure and phase composition of the CrFeCoNiAlx high-entropy alloy in-situ manufactured by powder bed fusion additive technique. The influence of a homogenization annealing at 1200 degrees C is also presented. The presence of Al powder in the pre-mixed blend decreased the porosity in the as-built samples, while the microhardness did not change significantly. All samples with different Al content demonstrated the chemical inhomogeneity, additionally the Al volatilization was observed. The annealing homogenized the material but led to the Al-rich precipitates. Additionally, the microhardness did not drop significantly for annealed CrFeCoNiAlx samples. The fraction of annealing twins in CrFeCoNiAlx was much lower than in CrFeCoNi after annealing at 1200 degrees C. According to XRD analyses, only the fcc phase was determined for all conditions.