Estudo da cinética de formação da liga pd-si amorfa.

Abstract

The critical cooling rate for formation of amorphous structure, tc, of the alloys Pd82 Si18 and Pd84 Si16, were calculated from the TRC diagram, according to the D.R.Uhlmann model. The influence of the approximations used to express the free volumetric energy variation of GIBBS, AGv, and to express the viscosity variation, n (T), with the temperature in the super cooled zone, on the calculated TC values, were analyzed. The TC values ​​calculated in this work for both compositions of the Pd Si alloy are in agreement with the experimental data reported in the literature when using the JD Hoffmann approximation for AGv and the equation of P. Ramachandrarao based on the expression of Doolitle, to describe the viscosity in the super cooled region. By the present study, the applicability of the D.R. Uhlmann model for CT calculation was demonstrated, demonstrating, however, the great sensitivity of these calculated values ​​to the approximations applied in the calculation of the CRT diagram.