Concentration, temperature and deformation dependences of martensite lattice parameters in binary Ti-Ni shape memory alloys

X-ray diffractometric study of Ti-47.0 to 50.7 at. % Ni alloys has been performed. A concentration dependence of B19' Martensite Lattice Parameters (MLP) exists in the range from 50.0 to 50.7 % Ni. MLP in Ti-47.0 and 50.0 % Ni coincide. Temperature dependence of MLP exists; MLP change in Ti-50.0%Ni alloy is enhanced in the B19' to B2 transformation range. In the Ti-50.0% Ni, MLP are different for the quenched martensite and for the one formed from the austenite containing well-developed dislocation substructure. In Ti-50.0% Ni alloy, MLP do not change after its deformation up to 25% strain. Changes in MLP in the case of hyper-equiatomic nickel concentration or due to the presence of highly-dislocated initial austenite are independent of the presence of the R phase during martensite formation.