Isothermal Crystallization Kinetics of an Amorphous CuTi Alloy
摘要
Isothermal crystallization kinetics of Cu_(40)Ti_(60)amorphous alloy has been studied using differential scanning calorimetry(DSC).Both as-quenched and pre-annealed ribbons were inves- tigated.For crystallization of as-quenched amor- phous ribbon in Ar,it was found that the kinetics follows Johnson-Mehl-Avrami equation with mean Avrami exponent n=2.58,which indicates that crystallization of amorphous Cu_(40)Ti_(60)is a three-dimensional diffusion controlled growth pro- cess with constant nucleation rate,i.e.,primary crystallization process.The primary phase is the tetragonal CuTi_2.The as-quenched amorphous ribbons were also crystallized in air,the results re- veal that oxidation has no significant influence on crystallization kinetics of amorphous Cu_(40)Ti_(60). The results of crystallization of pre-annealed rib- bons show a decreasing tendency of Avrami expo- nent with increasing pre-anneal time.The local activation energy and local Avrami exponent dur- ing crystallization process of as-quenched amor- phous alloy were also examined.