In the present work we study crystallization of the Ti50Ni22Cu22TM6 (TM stands for other transition metals: Cr, Mn and Fe) glassy alloys produced by rapid solidification of the melt. The effect of the additional transition metals Cr, Mn and Fe in stabilization of a cP2/B2 type phase is clarified in comparison with the base ternary Ti50Ni25Cu25 alloy. The transformation temperature and heat effects were studied by differential scanning calorimetry. The structure of the samples in the as-prepared and annealed states was examined by X-ray diffraction and transmission electron microscopy. Polymorphic transformation mechanism leading to the formation of the cP2/B2 type phase is studied in detail. Crystal nucleation and growth initiate on the free surface of the Fe-bearing alloy leading to the strong< 100 >texture formation and weak exothermic reaction which changes the shape of the DSC curves. On the contrary, the crystallization occurs within the entire volume of the Mn- and Cr-containing samples, indicating the effect of nucleation and growth of pre-existed nuclei in the glassy state on the heat release of crystallization and the resulted microstructure.
- Metallic glass
- Shape memory