An Analysis of Lattice Strain due to Disclination Dipole Walls in Fe–Pd Martensite

Abstract

The martensite structure in Fe–Pd is shown to possess disclination dipole walls, which induce a locally fluctuating residual stress field. In a polycrystal, the residual stress averaged over each (former austenite) grain vanishes, since the average transformation strain is the same for all grains. Thus, the stress fluctuations within each grain contribute to diffraction line broadening. A simple method is developed to evaluate the average of the square of the residual strain, which is directly related to the line broadening. The method consists of evaluating the elastic energy produced by the domain walls. The structural parameters, such as disclination dipole wall spacing, are also discussed in terms of the elastic energy.