Dislocation structure of refractory metal single crystals after high-temperature creep—X-ray diffraction study

The dislocation structure of low molybdenum alloys doped with niobium was studied by X-ray diffraction methods, namely by Berg-Barrett topography and by the double-crystal technique. As a result, the following model of misoriented cell structure after high-temperature creep is suggested. Cell boundaries were supposed to be formed by tilt walls of equidistantly spaced dislocations, while cell dimensions were obtained from X-ray topograms and metallographic images. For this model, X-ray rocking curves were calculated in the framework of Krivoglaz's diffraction theory; the calculated diffraction profiles agreed well with the experimental profiles. It was shown that analysis of the azimuthal dependende of the rocking curve width enabled us to determine the misorientation between adjacent cells as well as the directions of the Burgers vector and of the dislocation line.