Structural-phase transformations in the zirconium single crystal under the pressure of the deformation
The structural-phase transformation in pseudo-single crystal of zirconium during deformation on Bridgman anvils at room temperature with applied pressure up to 8 GPa is studied by X-ray diffractometry with synchrotron radiation. The angles of rotation in the Bridgman anvils turning varied from φ = 0 deg (deformation by draft) to φ = 45 deg. This method allows to evaluate the structural state of a sample throughout its thickness and to calibrate a state with a more accurate estimate of the true strain. It was shown that the α-phase lattice is compressed at a true strain value e = 4.6, which is reflected in its parameters: the α-phase parameter “α” decreases by 5.3 %, and the parameter “c” by 0.3 %. On the contrary, the ω-phase arising in the process of deformation under pressure showed a tendency to stretching, if the parameter “a” of this phase practically does not change with an increase in the degree of deformation, then the parameter “c” is insignificant, by 0.14 %, but increases. This behavior can probably be explained by the small atomic density and strong anisotropy in terms of the atomic density of the planes and series of the ω-phase. It is determined that the structure arising in the process of deformation of the baric ω-phase, deformation conditions from e = 0.5 to e = 4.6, does not undergo textural changes. At this step of deformation, only the stage of nucleation of the ω-phase is observed only in area of the α-phase, which have a favorable crystallographic orientation. The formation of groups of planar defects in the ω phase is a mechanism for the compensation of elastic stresses during lattice transformation α → ω under conditions of high quasihydrostatic pressure.