Characterization of Laser Beam Welded Al_0.5CoCrFeNi High-Entropy Alloy

Abstract

High-entropy alloys (HEA), a new generation alloy system offer superior mechanical properties with solid solution strengthening. AlxCoCrFeNi-HEA is one such system being received more attention because of its specific yield strength and ductility. In the present work, Al0.5CoCrFeNi-HEA was prepared by vacuum arc melting. The laser beam welding (LBW) was carried out on 1mm thick forged and homogenized HEA, with a beam power of 1.5 kW and at a traverse speed of 600 mm/min. The microstructural features of different regions of the weld were studied using scanning electron microscopy. The homogenized Al0.5CoCrFeNi-HEA have shown equiaxed grains of average size 60 μm. The weld metal showed a typical weld fusion zone microstructure with dendritic structure with a reduction in BCC phase due to minimal Al and Ni segregation ratio at interdendrites. Micro-chemical analysis with energy dispersive spectroscopy confirmed that there was no major segregation of elements in the weld fusion zone. The microhardness survey performed across the weld evidenced a reduction in hardness, as a consequence of significant reduction in Al-Ni rich hardening factor.

Welding of High Entropy Alloys—A Review

“…For Al0.5CoCrFeNi, the elemental analysis in FZ revealed that the dentrites were rich in Fe and Co, depleted of Al and Ni, and had an even distribution of the Cr element [ 19 ]. Similar results have been observed in LBE of Al0.5CoCrFeNi [ 30 ]. It is not fully clear if evaporation of Al had played role influencing the structure and properties.…”

“…For HEAs, hardness drop in the FZ was observed for Al0.5CoCrFeNi in laser and arc welding, while the hardness drop for CoCrFeMnNi is relatively limited or slightly increased. Sokkalingam et al [ 19 , 30 ] suggested that the hardness drop for the Al0.5CoCrFeNi in the LB weldment was due to the reduction of the hardening factor (Al-Ni rich BCC phase) in the weld metal than in the base metal. The processing method of the sample also influences the hardness changes.…”

“…Research on laser beam welding (LBW) of HEAs has been reported in several recent publications [ 26 , 27 , 28 , 29 , 30 ]. In a laser welding process, pieces of metal are melted and joined through a concentrated heat source provided by the laser beam, forming a narrow, deep weld ( Figure 4 a).…”

“…Composition distribution and element segregation across the welded joint at macro and micro scales are important to the understanding of the mechanical and corrosion resistance of the welded joint, which may be associated with many different mechanisms, such as evaporation, time and temperature for element diffusion, oxidation and precipitation, etc. [ 4 , 19 , 20 , 30 , 41 , 42 , 43 ]. For CoCrFeMnNi alloy [ 20 ], the GTA weld exhibited microsegregation behaviour in the Mn- and Ni-rich interdendritic region and Co-, Cr-, and Fe-rich dendrite cores, but the depletion of Mn was not observed, while for EBW weld, there was clear Mn depletion in the FZ ( Figure 11 ) [ 20 ].…”

Tungsten Matrix Composite Reinforced with CoCrFeMnNi High-Entropy Alloy: Impact of Processing Routes on Microstructure and Mechanical Properties

“…Researchers around the globe are extensively working on HEA research, and designing HEAs to tailor and improve the properties of the engineering materials [25][26][27]. One such application is the use of HEA as a reinforcement/binder in the metal matrix composites [28][29][30].…”