Microstructure and mechanical properties of CoCrFeNiMn HEA/1060Al magnetic pulse welded joints

Abstract

CoCrFeNiMn high entropy alloy and 1060 Al can achieve high quality welded joints using magnetic pulse welding. The mechanical properties and microstructure observation were used to evaluate the joint properties and the dynamic deformation mechanism of welded joint. The findings of the quasi-static tensile test indicate that as the discharge energy increases, the fracture of the joint is keeping at 1060 Al, and the fracture form of the joint undergoes a transformation, shifting from a ductile fracture to a ductile-brittle mixed fracture. The higher the discharge energy is, the interface transition layer and mechanical interlocking become more pronounced, exhibiting distinctive interface characteristics such as “wavy” and “inverted hook-like” patterns. The transition layer of the welded joint is primarily constituted of amorphous phases comprising Al, Co, Cr, Fe, Ni and Mn, along with substantial granular AlxCoCrFeNiMn high entropy alloy. The primary bonding mechanisms of CoCrFeNiMn high entropy alloy/1060 Al welded joints are local melting and rapid solidification. The dynamic deformation mechanism of the CoCrFeNiMn high entropy alloy matrix under an extremely high strain rate (10⁶–10⁷ s⁻¹) of electromagnetic pulse shock is dominated by dislocation motion, rather than the more commonly observed twins and adiabatic shear bands.