Effect of electropulsing treatment on microstructure and mechanical properties of Cu–20Ni–20Mn alloy

Abstract

The microstructure evolution and mechanical properties changes of the deformation-aged Cu–20Ni–20Mn alloy during electropulsing treatment (EPT) were investigated. The results indicate that, compared with the deformation-aged Cu–20Ni–20Mn alloy with a tensile strength of 942 MPa and an elongation of 1.4% in the previous study, the tensile strength and elongation of the deformation-aged Cu–20Ni–20Mn alloy after EPT with je (the root-mean-square value of pulse current density) of 10.7 A/mm2 for 150 s increased to 950 MPa and 11.3%, respectively. Fine recrystallized grains, local high density dislocation tangles and local uniformly distributed θ-MnNi phases were found in the microstructure of alloy after EPT, which played a key role in improving the strength and ductility of alloy simultaneously. The θ-MnNi phases distributed in the vicinity of dislocation tangles were more preferentially dissolved into the α-Cu matrix under the thermal effect and athermal effect of EPT than the θ-MnNi phases at grain boundaries. The kinetic energy from electron momentum (athermal effect) provided by EPT, which triggered the atomic diffusion accompanied by dislocation movement, leading to the acceleration of recovery, recrystallization processes of alloy and the dissolution of θ-MnNi phases. The results provide guidance for the strength-ductility simultaneous enhancement of various metallic materials.