Title screen

[References: 16 tit.]

Transmission electron microscopy (TEM) investigations were carried out to study the structural-phase state of ultra-fine grained (UFG) titanium with the average grain size of ~0.2 and 0.3 [mu]m, implanted with aluminium ions. MEVVA-V.RU ion source was used for ion implantation under room temperature, exposure time of 5.25 h, at ion implantation dosage of 1´1018 ion/cm{2]. UFG-titanium was obtained by means of multiple uniaxial compacting with multipass rolling in grooved rolls and further annealing at 573 K during 1 hour to reach the average grain size of ~0.2 [mu]m, and annealing at 623 K during 1 hour to reach the size of ~0.3 [mu]m. The study revealed that in alloy with the average grain size of ~0.2 [mu]m implantation results in a decrease in longitudinal grain size of [alpha]-Ti (from 1.9 to 0.7 [mu]m), however lateral size in its turn changed insignificantly (from 0.15 to 0.12 [mu]m). Grain anisotropy factor decreased by 3 times. In the alloy with the average grain size of ~0.3 [mu]m both longitudinal and lateral grain sizes decreased (from 0.33 to 0.19 [mu]m and from 2.1 to 0.8 [mu]m correspondingly). The studies also showed that implantation of titanium with aluminium has led to the formation of a number of phases, such as: [beta]-Ti, TiAl[3], Ti[3]Al, TiC and TiO[2]. Their places of concentration, sizes, distribution density and volume ratios were determined. TiAl[3] and Ti[3]Al phases were established to be ordered ones, formed within the conditions of ion exposure along the boundaries of [alpha]-Ti grains. Conducted calculations demonstrated that implantation contributed to the alloy strengthening, i.e. in alloy with the average grain size of ~0.2 [mu]m the value of yield stress increased by 2 times, and in the alloy with the average grain size of ~0.3 [mu]m-by 4 times.