Structural -- Phase Transformation in Two-Phase Titanium Alloys at Shock Loading

Plane targets from ($\alpha$ + $\beta$) Titanium alloy VT6 loaded under uniaxial strain conditions at the impact velocities from 400-600 m/s. The investigations were carried out on thickness of sample along the shock wave propagation, both in the central zone, and on distance 4, 7 and 11 mm from the centre. As it have shown results of microhardness, X-ray analysis, REM and TEM investigation, on an input in material of sample the shock loading wave resulting in decomposition of $\beta$-phase and enrichment by vanadium of $\alpha$-phase up to formation soft orthorhombic martensite - phase, braking shock wave was formed. The shock wave was reflected from opposite side on output and the wave of unloading was formed. Here there was a change of the mechanism of plastic deformation from shift to rotational. Thus there was an intensive heat-generating and return phase transformation, at which soft $\beta$-phase enriched with vanadium, inclined to decomposition down to formation of a brittle $\omega$-phase was formed. Than the more the quantity of soft $\beta$-phase, the microhardness of opposite side material was less. From the moment when $\beta$-phase turned in brittle $\omega$-phase, the hardness of sample material was raised. In this place the crack was formed.