Dislocation densities in soft and hard oriented grains of compression deformed textured NiAl polycrystals

Abstract

NiAl polycrystals with different textures have been compressed at room temperature with and without confining pressure to strains of 6 and 30 %, respectively. Grain orientation dependent dislocation densities have been determined by X-ray line profile analysis using the multiple whole profile procedure. The dislocation density as well as the stored energy in hard grains, <100> oriented with respect to the compression axis, generally is about half of that in soft grains, which are randomly oriented. Taking into account appropriate individual dislocation contrast factors it has been found that in hard grains slip mainly takes place by <111> screw dislocations while in soft grains there is about a 50 % contribution of mixed type <100> dislocations. The results are discussed with respect to the inhomogeneity of deformation of plastically anisotropic materials and its effect on recrystallization.

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

“…However, in the axial-case (open circles) the 2 0 0 reflection shows a much smaller broadening, indicating that these two reflections sample two different grain populations. Table 3 The largest Schmid factors of the three different possible slip systems [44,45] for the three different main texture components [36]. The evaluation is continued by considering the plastic response and the slip systems in the different texture components.…”

“…In the other two grain populations all possible slip system types can be activated. Plastic deformation of the 1 0 0 oriented grains is much more difficult than the other populations, therefore the 1 0 0 and the other populations are denoted as hard and soft grains, respectively [36].…”

“…The X-ray beam and detector system was the same as described in paragraph 4. Two surfaces were cut on the specimens: one perpendicular, and one parallel to the loading direction, denoted axial-and side-case, respectively [36]. The specimens were mounted in an Eulerian cradle in order to orient the major texture component into diffraction condition for each measured reflection.…”

Elastic properties of B2-ordered NiAl and NiAl–X (Cr, Mo, W) alloys

“…Also crystal plasticity and strengthening mechanisms in metal physics as well as high temperature plasticity and creep of polycrystalline materials are somehow related to elastic quantities, such as Young's and shear moduli, respectively [11][12][13][14][15].…”

Evaluation of microstructure anisotropy on room and medium temperature ECAP deformed F138 steel

“…When the orientation distribution of crystals is not random the tactic of calculating average contrast factors does not hold because the actual average must be done over the total product ρC considering the preferential orientation of the crystals. Those calculations cannot routinely be performed yet but, only in a few particular cases, some assumptions could be made to better analyze the data [44]. In the current case the textures correspond to typical preferential orientations obtained by shearing where the strengths are not too high and the components are not highly developed.…”