A constitutive modelling approach, called the disturbed-state concept, was developed in order to characterize the mechanical response of material which contained dislocations and O impurities. Factors such as the dislocation density, temperature, strain-rate and O concentration were included in the model. The parameters for a Si crystal, with or without O impurities, were calibrated on the basis of published stress-strain data. The predictions of the disturbed-state concept model were compared with those based upon the Dillon model, and with test data. It was found that the correlation between the present predictions and the test data was very good. It was suggested that the disturbed-state concept could provide a unified and improved constitutive model, in comparison with previously available models, for the thermomechanical behavior of Si and other materials.

Disturbed state constitutive model for thermomechanical behavior of dislocated silicon with impurities C.S.Desai, T.J.Dishongh, P.Deneke: Journal of Applied Physics, 1998, 84[11], 5977-84