Characterization of the microstructure in random and textured polycrystals and single crystals by diffraction line profile analysis

X-ray or neutron diffraction patterns are simulated by convoluting defect specific profile functions based on continuum theory of elasticity. The defect related profile functions are controlled by the physically mandatory minimum number of parameters: the dislocation density, ρ, the dislocation arrangement parameter, M, one or more parameters describing strain anisotropy where their number depends on the crystal symmetry, the median, m and the logarithmic variance, σ of the log-normal size distribution function, and finally the density of stacking faults, α or the frequency of twin boundaries, β. These parameters are, at the same time, among the most relevant physical parameters describing the microstructure of crystalline materials. The theoretical diffraction patterns are produced by the convolution of the defect related, physically based profile functions in the “extended Convolutional Multiple Whole Profile” (eCMWP) software package. The usage of the software package is demonstrated by the microstructure determination in randomly-textured and textured polycrystalline and single crystals specimens of different materials.

Research highlights▶ X-ray or neutron line profile analysis becomes a powerful tool to characterize dislocation structures, crystallite size, size-distribution and planar faults when diffraction patterns are constructed by the bottom-up approach following physical principles. ▶ The microstructure of archaeological specimens can tell about the manufacturing technologies used by our ancestors. ▶ Burger vector and slip system types operating in grains of polycrystal enable to understand plastic response in structural materials and geological minerals. ▶ The type and frequency of twinning in hexagonal materials is essential to understand the durability of key engineering materials in energy production.