OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 3 2022 with an average grain size in the longitudinal and crosssection directions of about 50 μm (Fig. 3, a, b). Thin bands of the martensite located inside the grains are observed. The presence of residual austenite is not excluded. The clusters of (Ti, Hf)2 Ni type particles of the excess phase, formed immediately after melting, are observed at the grain boundaries [10]. It is assumed that the phase composition of the alloy at room temperature consists of a mixture of martensite, a small amount of residual austenite and the (Ti, Hf)2 Ni phase with a volume fraction of about 20–25 %, estimated visually. The platelet shape of the intragranular phase and the results of the XRD study (Fig. 3) confi rm this suggestion. Rolling with current leads to a change in the morphology of the grain structure: it becomes more elongated (Fig. 4, c). At the same time, an even more pronounced grain elongation in the transverse direction is observed (Fig. 4d), which may be explained by both the geometry of the sample and the features of the plastic fl ow of the alloy during rolling with current. This leads to a redistribution of particles of the (Ti, Hf)2 Ni phase, which line up along the elongated boundaries of structural elements formed during rolling with current. It should be noted that, despite the large number of macrocracks on the side edges of the strip after rolling, intergranular and intragranular microcracks were not found at all stages of deformation. Fig. 3. X-ray diffraction pattern of the alloy in the initial state Fig. 4. Microstructure of the alloy in the initial (a, b) and current-rolled (c, d) states: a, c – along the rolling direction; b, d – across the rolling direction a b c d
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