Primary crystallization mechanisms of chalcogenide amorphous alloys

FONTANA, M.; MARIA ANDREA UREÑA; ARCONDO, B.; MORA, M. T.; CLAVAGUERA, N.

Cancun, Mexico

Congreso; XIV Internacional Materials Research Congress y Simposio Inter-American Colaboration in Materials (CIAM); 2005

The knowledge of the microscopic mechanisms for primary crystallization of glassy alloys allows the micro structural control for optimizing properties. In this respect, the differential scanning calorimetry (DSC) has been widely used for the determination of both the thermal stability of the glassy alloys and the apparent activation energy of crystallization. Most methods for the kinetic analysis of crystallization processes consider the “isokinetic” hypothesis: the transformation rate dx/dt can be expressed in terms of a first-order separable differential equation: dx/dt = k(T)/P(x) where k(T) is the rate constant that depends only on the absolute temperature T, P(x) reflects the mechanisms driving the reaction and x the transformed fraction. A new procedure, which has been recently developed (*), was applied to perform the kinetic analysis of isothermal and continuous heating calorimetric data of chalcogen glassy alloys crystallization. This method was applied to the kinetic study of the crystallization process of amorphous alloys of the systems GaTe and GeSeAg obtained by rapid solidification. Kinetic information was obtained from X-ray diffraction and calorimetric measurements. The main objective of this work is to use the recently introduced master curve method (*) to establish a firm basis for modeling primary crystallization of chalcogen glasses.   (*) D.Jacovkis, Y.Xiao, J.Rodriguez-Viejo, M.T.Clavaguera Mora and N.Clavaguera, Acta Materialia 52 (2004) 2819-2826.