2019 Volume 98 Issue 7 Pages 157-164
In order to improve the compressor cycling stability and hydrogen storage properties of V40Ti21.5Cr38.5 alloy further, the fourth element i.e. Niobium, Iron, or Zirconium has been substituted for Cr to prepare V40Ti21.5Cr33.5M5 alloy and their cyclic hydrogen absorption-desorption performance was evaluated up to 100 cycles for temperature and pressure ranges of 20-300 °C and 5-20 MPa, respectively. All the three compositions have shown different sorption properties as well as cyclic stability. The V40Ti21.5Cr33.5Nb5 alloy was found a most suitable composition with a comparatively high hydrogen capacity and reasonable stability after 50 cycles of compressor cyclic test, whereas, V40Ti21.5Cr33.5Fe5 alloy has shown worst cyclic stability with lowest hydrogen capacity. However, structural and morphological investigations suggest no phase segregation during the cycling of V40Ti21.5Cr33.5Fe5 alloy in contrast to the other alloys, which suggest that phase segregation is not the only responsible reason for the performance degradation of BCC alloys employed for compressor cycle. In some cases similar to V40Ti21.5Cr33.5Fe5, stress/strain formation in the lattice during cycling may also cause the degradation of the material.
