The effect of H treatments upon lattice defects in the  phase was investigated by using optical and electron microscopy, and positron annihilation techniques. It was found that the numbers of defects in hydrogenated specimens were much higher than those in de-hydrogenated specimens. The defects which were generated by hydride formation were mainly dislocations. Vacancy-like defects predominated as the H content was increased.

C.Zhang, Q.Kang, Z.Lai, R.Ji: Acta Materialia, 1996, 44[3], 1077-84