The effect of Nb addition on the microstructural, mechanical and electrochemical characteristics of AlCrFeNiCu high entropy alloy

Abstract

AlCrFeNiCuNb(subx) high entropy alloys were successfully fabricated using laser metal deposition technique. Laser power of 1600W and scanning speed of 1.2 m/min were used during the processing of the alloys. The microstructural, mechanical and electrochemical characteristics of the alloys were evaluated using various advanced characterization techniques. The results revealed that the alloys exhibited dual phase structure with dendritic grains. The inclusion of Nb in the AlCrFeNiCu alloy matrix promoted the formation of fine eutectic structures and changed the shape of the grains from columnar to aquiaxed. The content of Ni+Cu decreased with rising concentration of Nb while Al was increased. The findings gave evidence that the presence of Nb in the alloy favored formation and stability BCC phase. All the alloys that contained also Nb exhibited elevated hardness, high compressive strength and better wear resistance. Furthermore, the lower current density and positive shift in potential highlighted the superior anti-corrosive properties exhibited by HEAs with higher Nb content.