STRUCTURES AND PHASE TRANSITIONS CRISTALLOGRAPHIC STRUCTURES OF AUSTENITIC AND MARTENSITIC HYDRIDES OF Ti0.64Zr0.36Ni INTERMETALLIC COMPOUND

TiNi alloy is polymorphic. It exhibits a martensitic transition near room temperature between a cubic CsCl-type (austenite) and a monoclinic TiNi-type (martensite) structure. This transformation is at the origin of its shape memory effect. In addition, TiNi has good hydrogen storage properties under normal conditions of pressure and temperature. In austenic form, TiNi absorbs 1.4 H/f.u. under atmospheric pressure. No plateau is observed in the pressure composition isotherm curve (PCI) showing that hydrogen is absorbed in solid solution [1]. Hydrogenation properties of the martensite form are unknown. By adjusting a partial substitution of Ti by Zr and by using different elaboration techniques (melt spinning and induction melting)