Effect of Severe Plastic Deformation on Structure and Properties of Al-Sc-Ta and Al-Sc-Ti Alloys

Abstract

The comparative analysis of the effect of monotonous and non-monotonous severe plastic deformations (SPD) on the structure and properties of aluminum alloys has been carried out. Conventional hydrostatic extrusion (HE) with a constant deformation direction and equal-channel angular hydroextrusion (ECAH) with an abrupt change in the deformation direction were chosen for the cases of monotonous and non-monotonous SPD, respectively. Model cast hypoeutectic Al-0.3%Sc alloys and hypereutectic Al-0.6%Sc alloys with Ta and Ti additives were chosen for studying. It was demonstrated that SPD of the alloys resulted in the segregation of the material into active and inactive zones which formed a banded structure. The active zones were shown to be bands of localized plastic deformation. The distance between zones was found to be independent of the accumulated strain degree and was in the range of 0.6–1 μm. Dynamic recrystallization in the active zones was observed using TEM. The dynamic recrystallization was accompanied by the formation of disclinations, deformation bands, low-angle, and high-angle boundaries, i.e., rotational deformation modes developed. The dynamic recrystallization was more intense during the non-monotonous deformation as compared with the monotonous one, which was confirmed by the reduction of texture degree in the materials after ECAH.

Mechanical properties and structural stability of a bulk nanostructured metastable aluminum-magnesium system

“…Several reports are currently available for estimating the crystallite sizes and microstrain from analyses of X-ray diffraction data on bulk nanostructured materials processed by SPD techniques [66,[82][83][84][85][86], nanomaterials synthesized by powder metallurgy and a mechanical alloying approach [72,[87][88][89][90][91][92] and nanoparticles and thin films [93][94][95][96]. These results are summarized in Fig.…”

“…Fig. 6 A plot of the microstrain versus crystallite size measured by XRD analysis on bulk nanostructured materials processed by SPD [66,[82][83][84][85][86], nanomaterials synthesized by powder metallurgy and a mechanical alloying approach [72,[87][88][89][90][91][92] and nanoparticles and thin films [93][94][95][96].…”

Thermoelectric Method of Plastic Deformation Detection

“…The proposed method takes advantage of the thermoelectric effect, which is based on the fact, that in a closed circuit consisting of two dissimilar conductors, where the junctions are at different temperatures, a resulting current occurs [12][13][14][15][16][17][18][19]. In the case of heating the contact of two samples to a temperature T 2 , the energy of the electron output at the point of contact is different, and an electromotive force accordingly occurs in the electrical circuit [20][21][22][23][24][25].…”