Crystallization behavior of cold worked Ti-30Ni-20Cu(at%) alloy ribbons

Abstract

Amorphous Ti-30Ni-20Cu(at%) ribbons were cold rolled by 30%, then crystallization behavior was investigated by means of optical microscopy, transmission electron microscopy, scanning electron microscopy and differential scanning calorimetry. Although cold working did not bring about deformation-induced crystallization, it reduced activation energy for crystallization from 198.8 kJ/mol to 121.7 kJ/mol and lowered exothermic peak temperature (T-p) for crystallization from 755-769 K to 730-751 K, suggesting that it assists crystallization of amorphous Ti-30Ni-20Cu(at%) ribbons. Cold working induced inhomogeneous grain size distribution after crystallization, reduced average grain size, widened transformation range and raised martensitic transformation temperatures, which were ascribed to a strain field introduced during cold working. (C) 2010 Elsevier Ltd. All rights reserved.