Effect of solidification rate on the phase structure and electrochemical properties of alloy Zr0.7Ti0.3(MnVNi)2

In this work, the alloy Zr0.7Ti0.3Mn0.4V0.4Ni1.2 is selected and prepared through both arc-melting and melt-spinning processes at different solidification rates. The electrochemical tests have indicated that higher solidification rates lead to a higher discharge capacity when the solidification rates were <10 m s-1 and a lower discharge capacity when solidification rates were >10 m s-1. When solidification rates get higher, the cycling stability improves, but the activation property and the high-rate dischargeability of the melt-spun alloy both get worse noticeably. The XRD results indicate that the as-cast alloy and the melt-spun alloys all contains two Laves phases, C14 and C15, but the phase composition and phase abundance of the alloys are quite different from each other. The SEM and EPMA results indicate that the microstructure of melt-spun alloy is a uniform mixture of very fine dendritic and columnar crystalline structures, while the as-cast alloy is of much coarser dendritic crystalline structure with noticeable composition segregation. It is the difference in phase composition, phase abundance, and microstructure that results in the noticeable difference in electrochemical properties