On the experimental verification of an atomistic model for boundary sliding controlled optimal superplastic flow

Optimal superplastic deformation is best explained when it is assumed that Grain/Interphase Boundary Sliding (GBS) controls the rate of flow. Based on this premiss an atomistic model for GBS controlled optimal superplastic flow has been presented. A computational procedure for the numerical verification of superplasticity data has also been developed. In the presence of a finite long range threshold stress arising from mesoscopic sliding, the rate equations could not be solved easily owing to their transcendental nature. Therefore, a simplifying assumption of neglecting the threshold stress was made and a procedure to solve the equations given. Superplasticity data pertaining to different alloy systems were then analyzed. The true activation energy for the rate controlling process and the different deformation parameters were determined for various systems. The strain rates were then repredicted for different stress levels. It was seen that this model is capable of predicting the strain rates accurately even though a simplifying assumption of neglecting the long range threshold stress was made.