A generalized hard-sphere model for the irradiation induced viscosity of amorphous binary alloys

The entropy of mixing of binary alloys using a generalized hard-sphere model of binary fluids is considered in an application to alloys that undergo an irradiation-induced crystalline–amorphous transformation at temperatures significantly below the melting temperature. The model is based on the observation that many amorphous materials respond in a “liquid like” manner while under irradiation. The generalization of the model to include attractive forces is obtained by adding the effect of a uniform negative background potential to the hard-sphere model. An application of the method is demonstrated for U–Si, U–Al and Al–Si irradiated alloys. Because of the scarcity of experimental information, estimates of the binary alloy formation enthalpy made using the empirical Miedema method are employed. Thermal expansion coefficients are estimated using the quantum approximate BFS method assuming solid solution. The model is used to calculate the viscosity of the alloys as a function of composition.