Journal of Welding Science

In this study, gas-tungsten arc welding was used for the cladding of two high entropy alloys of AlCoCrFeNi (Al1) and Al0.7CoCrFeNi (Al0.7) onto plain carbon steel plates. The welding process was carried out at a welding current of 180 A and a welding speed of 1.4 mm/s. The microstructures, craking behavior, phase composition, and hardness of the clads were characterized using various methods, such as optical microscopy (OM), field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD) analysis, and microhardness measurements. The results indicated that the Al1 clad had a petal-like structure of the BCC and Cr-rich phases. Both intergranular and transgranular cracks were identified in the Al1 alloy, which were recognized to be solidification cracks. Thermal stress and brittleness of the BCC phase promote cracking of the Al1. On the other hand, in the Al0.7 alloy, in addition to the BCC phase, a new FCC phase was  formed with various Widmanstatten and dendritic morphologies in the clad microstructure and the Cr-rich phase was not observed. Furthermore, in this alloy with lower Al content, a crack-free clad was obtained. The crack prevention in the Al0.7 alloy was attributed to a combination of factors, including a decrease in the solidification range, formation of the FCC phase, and reduction in hardness.