A method for intragranular orientation and lattice strain distribution determination

A novel approach to quantifying intragranular distributions is developed and applied to the α → [epsilon] phase transition in iron. The approach captures both the distribution of lattice orientation within a grain and the orientation dependence of the lattice strain. Use of a finite element discretization over a ball in Rodrigues space allows for the efficient use of degrees of freedom in the numerical approach and provides a convenient framework for gradient-based regularization of the inverse problem. Application to the α → [epsilon] phase transition in iron demonstrates the utility of the method in that intragranular orientation and lattice strain distributions in the α phase are related to the observed [epsilon] orientations. Measurement of the lattice strain distribution enables quantitative analysis of the driving forces for [epsilon] variant selection. The measurement and analysis together indicate quantitatively that the Burgers mechanism is operative under the experimental conditions examined here.