The effects of rapid solidification on microstructure and hydrogen sorption properties of binary BCC Ti-V alloys

The main purpose of the present work was to study the effect of rapid solidification (RS) on the microstructure and hydrogen storage properties of body centred cubic (BCC) Ti rich Ti-V alloys (Ti1-xVx, x = 0.1-0.3). Ribbons were prepared by melt spinning at spinner rotation velocities of 1000-3000 rpm. Ribbon morphology and microstructure were found to depend on the vanadium content and spinner velocity. For Ti0.8V0.2, the relation between the ribbon thickness and velocity can be expressed as a power law function, indicating that, during solidification of the Ti-V ribbons, heat transfer at the interface between spinner and ribbon controls the heat extraction. Temperature desorption spectroscopy (TDS) and in situ synchrotron (SR-XRD) studies of the RS alloys showed that hydrogen desorption from the RS alloy hydrides occurred at lower temperatures than from the as cast alloys. RS caused a microscale chemical element separation in the alloys, which depends on the vanadium content and the spinner velocity. In addition, ribbon recalescence was observed to cause nanoscale chemical redistribution trough spinodal decomposition. These two last features were proposed to be the reasons for the observed thermal destabilisation.