Hot isostatic pressing of ball milled novel grade high entropy alloys at different sintering time and the investigation of their mechanical and corrosion resistance properties

Abstract

With the discovery of high entropy alloys, new materials with superior properties have emerged. According to recent research, high-entropy alloys' multi-component structure and mixing entropy have made them more prominent than other alloys. Because of their excellent chemical and mechanical properties-such as high hardness, high-temperature resistance, high wear resistance, chemical stability, and high corrosion resistance-high entropy alloys outperform other material types in various applications. A new grade of mechanically alloyed high entropy alloy ( HEA ) of composition 23Fe-21Cr-18Ni-20Ti-18Mn was consolidated by a hot isostatic pressing ( HIP ) at a temperature of 1000 degrees C, at different sintering time of 30, 60, and 90 min respectively. We have investigated the impact of sintering time on the microstructure, mechanical, corrosion, and wear- resistance properties. The x-ray diffraction ( XRD ) spectra of the 30 min HIPed HEA sample showed dominant s-FeCr phases and traces of gamma-Fe, and the Ni-Ti phases. Whereas, the 90 min HIPed HEA samples showed more dominant Ni-Ti and traces of gamma-Fe, and beta-Mn phases. There is a phase transformation from BCC to HCP of consolidated HEA at increased holding time. The density of the samples increases from 5.882 to 6.327 g cm(-3 )and the porosity percentage decreases from 12.93 to 6.35% with the increase in the holding time. The Vickers microhardness value for 30, 60, and 90 min HIPed 23Fe-21Cr-18Ni-20Ti-18Mn HEA at 1000 degrees C was found to be 433, 513, and 793 HV respectively at an indentation load of 0.1 kgf. The consolidated HEA sample undergoes an abrasive and oxidative wear mechanism with ploughing and plastic deformation modes. The morphology of the wear debris was investigated using SEM. The 90 min sintered sample showed an excellent corrosion resistance due to the high rate of material densification and minimum surface fl aws.