Effect of chromium on elastic and plastic deformation of Fe₃Al intermetallics

In order to evaluate the effect of chromium concentration on the mechanical properties of single phase iron aluminum intermetallics, specifically those containing 26 at.% Al, a nano-indentation technique was used. The grain orientations of samples were revealed with the aid of Electron Backscatter Diffraction (EBSD) technique. Additionally, the surface roughness of each sample was checked after electropolishing with the aid of Atomic Force Microscopy (AFM). Finally, all nano- and micro-indents were performed within the (001) orientated grains, where the surface roughness was less than 1.06 nm on average, in all samples. The Oliver-Pharr method, with correction for pile up, was used to calculate the Young's modulus and nano-hardness for Fe₃Al-xCr alloys. Additionally, the effect of Cr on the shear stress needed for homogeneous dislocation nucleation, internal friction stress of dislocation motion (Peierls-Nabarro stress) and flow stress was studied.