INFLUENCE OF RAPID SOLIDIFICATION ON NI50-XTI50COX SHAPE-MEMORY ALLOYS

Rapidly solidified (R.S.) Ni50-XTi50CoX ribbons hal been produced by a single roller melt spinning technique. The influence of rapid solidif ication experimental parameters on the structure and transition behavi our were investigated by DSC, by X-ray diffraction and by TEM. The DSC curves are stable from the first cycle and a preferred orientation ex ists in the rapidly solidified NiTiCo alloys. An experimental paramete r such as quenching temperature increasing is followed by the precipit ate growth. These precipitates of Ti2Ni, may be responsible for the ma rtensitic and R transition temperature decreasing. Annealings enlarge the precipitate size and the transition temperatures decrease again.