Effect of Rapid Quenching in Magnetic Field on the Microstructures and Electrochemical Performances of AB5-Type Alloys

Abstract

Direct magnetic field was imposed during the process of rapid quenching by melt spinning of MlNi3.6Co0.7Mn0.4Al0.3 and MlNi3.6Co0.35Mn0.5Al0.3Cu0.25. The effect of rapid quenching in magnetic field on the microstructures and electrochemical performances was investigated in detail. The results show that rapid quenching decreases the grain size of both alloys, and magnetic field results in an oriented growth especially for MlNi3.6Co0.35Mn0.5Al0.3Cu0.25 alloys, but they have little influence on the typical CaCu5 structure of AB5-type alloys except for the increase of cell parameters (a0, c0) and cell volume. Electrochemical studies indicate that rapid quenching enhances the cycle stability significantly but inevitably decreases the electrochemical capacities of the alloys unless magnetic field was imposed. Additionally, the diffusion of hydrogen and rate properties are improved with the emergence of magnetic field compared with the alloys processed by rapid quenching only.