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 V 3Ti0.56Hf0.24Mn0.15Cr0.1 alloy were studied. It was found that the microstr ucture of the rapidly solidified alloy is composed of small dendrites excep t for the equiaxed grains near the ribbon surface. Compared with the induct ion-melted alloy, the rapidly solidified alloy has less of the C14-type sec ondary phase. The secondary phase is predominantly surrounded by the dendri te arms of the main phase in the rapidly solidified alloy. Furthermore, the re 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 induction-melted al loy. Even so, the cycle stability of the rapidly solidified alloy is improv ed. (C) 2000 Elsevier Science S.A. All rights reserved.