Investigation of the failure behaviour of equiatomic AlCrCuNiFe based high entropy alloy TIG weld cladding

Abstract

The present research focuses on the development of an equiatomic AlCrCuNiFe high entropy alloy (HEA) cladding using the TIG welding process. The influence and contribution of TIG cladding process parameters (welding current, welding speed, and SOD) on the microhardness and flexural stress have been investigated using the response surface methodology (RSM) and analysis of variance (ANOVA), respectively. The indentation fracture toughness test has been conducted over the claddings exhibiting minimum, maximum, and optimum microhardness values. The result revealed that welding current has the highest effect on the mechanical performance of the HEA cladding. The FE-SEM, optical microscopy, XRD and EDS analysis were performed to characterize the claddings. The cladding deposited at the S12 test run offered the least flexural resistance, microhardness, and indentation fracture toughness which was about 812 MPa, 494.97 HV0.3, and 1.29 ± 0.04 MPa.m1/2, respectively. In contrast, the optimized S5 cladding specimen exhibited good flexural resistance, appreciable microhardness and indentation fracture toughness of about 1543.92 MPa, 712 HV0.3, and 1.63 ± 0.03 MPa.m1/2 respectively. The optimum cladding exhibited flexural stress, microhardness, and fracture toughness enhancement of 46.77 %, 30 %, and 26.35 % compared to the least resistance cladding (S12) due to the high-retained alloying elements leading to enhanced solid solution strengthening. The three-point bend-tested cladding specimens’ optical microscopy images revealed that the cladding failure was primarily due to cohesive failure, crack progression, and delamination.