Structure and mechanical and electrochemical properties of ultrafine-grained Ti

Structure, unelastic properties, and deformation behavior of ultrafine-grained titanium

“…It was found in [3,7,[12][13][14][15][16] that the ultrafine-grained structure obtained in this case had an average grain-subgrain structure element about 350 nm, the smallest and the largest being 200 and V. D. Kuznetsov Siberian Physical-Technical Institute at Tomsk State University; Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No.…”

“…The formation of the above ultrafine-grained structure in titanium by equichannel angular pressing results in a significant increase in strength (yield stress σ 0.2 and ultimate strength σ В ) with preserving fairly high plasticity (uniform elongation δ В and total elongation to fracture δ f ) [3,7,12,15,[30][31][32]. A decrease in the size of grain-subgrain structure elements and in the fraction of large-angle grain boundaries with additional cold plastic deformation of ultrafine-grained titanium, however, leads to increased strength and decreased plasticity ( Table 1).…”

“…The low-temperature maximum is due to the boundaries of the general type, whereas the high-temperature maximum is caused by special and low-angle boundaries. In view of the fact, the temperature dependence of the internal friction Q -1 (T) under heating at a rate of 400 K/h (the frequency of torsional oscillations was about 1 Hz) was studied to reveal the effect of equichannel angular pressing followed by mechanical-thermal treatments on the unelastic grain-boundary deformation in titanium [3,[12][13][14][15][16]. On the basis of the data, the temperature of the onset and intensive development of unelastic grain-boundary deformation under the external force action was determined as well as the activation energy of the micromechanism responsible for this deformation.…”

“…In coarse-grained recrystallized titanium, as in other metals, grain boundaries are perfect [3,[12][13][14][15][16]. At the same time, grain boundaries formed under severe plastic deformation by equichannel angular pressing are imperfect (highly nonequilibrium) [3,[12][13][14][15][16].…”

“…At the same time, grain boundaries formed under severe plastic deformation by equichannel angular pressing are imperfect (highly nonequilibrium) [3,[12][13][14][15][16]. They are characterized by an increased grain-boundary self-diffusion coefficient [3,18].…”