METHOD OF PRODUCTION OF DOUBLE FORM MEMORY ALLOY AND METHOD OF MAKING ARTICLE FROM THIS ALLOY Russian patent published in 2003 - IPC

FIELD: production of double form memory alloys. SUBSTANCE: proposed method includes the following stages: (a) testing of untreated NiTi alloy for estimation of its internal structure by means of measurement of temperature difference between A_s and A_f, where A_s is temperature at which austenitic transformation starts (transformation from martensitic to austenitic state) and A_f is temperature of end of austenitic transformation; (b) first heat treatment of untreated NiTi alloy performed during period of time determined on base of difference of A_f and A_s according to results obtained at stage (a) for bringing the initial internal structure of alloy having practically stable density of distributed dislocations to preset state; (c) thermomechanical treatment of alloy including plastic deformation at simultaneous heating in the course of dynamic aging for obtaining polygonal subgrainy dislocation structure decorated by deposits; (d) intermediate heat treatment (if required) for completion of one cycle of forming of subgrainy dislocation structure; (e) performing stages (c) and (d) till finished form has been obtained and (f) final heat treatment and treatment for imparting required form. Proposed method ensures obtaining the alloy at reversibly controllable specific transformation temperatures without multi-cycle temper rolling . EFFECT: enhanced efficiency. 16 cl, 1 dwg