Microstructure and electrochemical behavior of a rapidly solidified V3TiNi0.56Hf0.24Mn0.15Cr0.1 hydrogen storage alloy

The microstructure and electrochemical behavior of the rapidly solidified V3TiNi0.56Hf0.24Mn0.15Cr0.1 alloy were studied. It was found that the microstructure of the rapidly solidified alloy is composed of small dendrites except for the equiaxed grains near the ribbon surface. Compared with the induction-melted alloy, the rapidly solidified alloy has less of the C14-type secondary phase. The secondary phase is predominantly surrounded by the dendrite arms of the main phase in the rapidly solidified alloy. Furthermore, there is a lot of fine particles with diameters of 5-20 nm precipitated in the matrix of the main phase. Precisely because of these microstructures, the rapidly solidified alloy has a lower reversible capacity, a worse high-rate dischargeability and a slower activation rate than the inductionmelted alloy. Even so, the cycle stability of the rapidly solidified alloy is improved.