Enhancement of tensile strength in AA 6061-T6 plates joined by gas tungsten arc welding using high entropy alloy filler sheet

Abstract

This work has focused on enhancing the tensile strength of AA 6061-T6 plates by gas tungsten arc welding (GTAW) using an AA 1100-O sheet embedded with a high entropy alloy (HEA, Cr0.14Fe0.13Al0.26Cu0.11-Si0.25Zn0.11) as a filler metal. HEA filler sheets were prepared by accumulative roll bonding (ARB). The prepared (AA 1100-O)-HEA filler metal was used to join the AA 6061-T6 plates. Phase formation and microstructural evaluations were carried out using an x-ray diffractometer and advanced electron microscopy in the (AA 6061T6)-HEA weldment. The phase evaluation results revealed the presence of HEA with Al peaks and unveiled FCC phase formations and disappearance of the BCC phase owing to the incorporation of more FCC elements and less solid dissolution. The major FCC phase is attributed to the atomic radius mismatch among the incorporated metallic elements. The retention of the HEA phase after welding indicated thermal stability and sluggish diffusion behaviour. (AA 6061-T6)-10 wt.% HEA welded plates exhibited higher strength and plasticity due to the presence of nanocrystalline HEA, superior interfacial bonding between AA 6061-T6 and HEA elements, and the involvement of solid solution (178 MPa), dislocation (152 MPa), and grain boundary strengthening (27 MPa) towards the total strength (357 MPa).