Crystallization of Mechanically Alloyed Ni50Ti50 and Ti50Ni25Cu25 Shape Memory Alloys

Abstract

The Ni50Ti50 and Ti50Ni25Cu25 alloys were produced in the form of powder using the high-energy ball milling. In the as-milled state, both alloys revealed presence of an amorphous state with a small amount of nanocrystalline areas. The non-isothermal DSC heating curves were used to investigate the crystallization process. Temperatures and activation energy of crystallization were determined. In both alloys, the crystallization occurred at temperatures range from 777 to 813 K, dependently on the heating rate. The activation energy values determined by the Kissinger and Ozawa method were comparable for both alloys and ranged from 410 to 429 kJ/mol.