On the effect of aluminum and chromium on the deformation twinning of body-centered cubic iron

Abstract

This paper reports on investigations on the effect of aluminum and chromium on the formation of deformation twins in body-centered cubic iron. For this purpose, impact loading experiments (ε = 104 s−1) were carried out at room temperature on samples of iron and the alloys Fe-10at.-% Al and Fe-10at.-% Cr. Furthermore, the grain size was varied in order to consider the effect of the alloying elements for both fine-grained and coarse-grained microstructures. The investigations on twin formation were carried out by electron backscatter diffraction (EBSD) and by quantitative image processing using optical microscopy. The observations show a comparable twin portion in iron and Fe 10at.-% Cr after impact loading for both grain sizes. In the alloy Fe-10at.-% Al the portion of twins is significantly increased for fine-grain and coarse-grain state. In order to clarify the possible reason, X-ray diffraction analyses (XRD) were additionally carried out. These show a shift in the reflexes which can be attributed to an elastic distortion of the lattice. This lattice distortion due to the formation of solid solution correlates very well with the determined twin fractions.