Crack elimination by Al concentration in GTAW- claded AlxCoCrFeNi high entropy alloy

Crack elimination by Al concentration in GTAW claded AlxCoCrFeNi high entropy alloy

In this study, two high entropy alloys of AlCoCrFeNi (Al1) and Al0.7CoCrFeNi (Al0.7), were cladded on plain carbon steel using the gas-tungsten arc welding process at a welding current of 180 A and a welding speed of 1.4 mm/s. Clads microstructures and types of cracks have been investigated by a combination of optical microscopy (OM), field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD) analysis, and microhardness measurements. Results indicate that the Al1 clads has a petal-like structure of the BCC phase and the Cr-rich phase at grain boundaries. Both intergranular and transgranular cracks were identified in the Al1 alloy. The type of crack was assumed to be a solidification cracking. By reducing Al in the Al0.7 alloy, the Cr-rich phase eliminated, and a new phase with the FCC crystal lattice formed in various morphologies. A combination of factors, including a decrease in the solidification range, formation of the FCC phase, and reduction in hardness, was attributed to crack elimination in the Al0.7 alloy.