Hydrogen influence on phase transformations in TiNi alloys with shape memory effect

Using the internal friction method and measuring both the shear modulus and the electric resistively allow to establish that hydrogen in TiNi alloys influences the sequence and strength of phase transformations when cooling down from temperatures where exists an homogeneous B2 phase. The successive sequence of phase transitions as fixed by the presence of hydrogen depends on the position of the martensite transformation relative to the temperature of hydrogen insertion. Thus, it is possible to activate the transition B2 $\rightarrow$ R and (or) to suppress a transformation of such a type