Structural and phase transformations in Zr and Zr–Nb alloys under loading by spherical converging stress waves

Abstract

Abstract X-ray diffraction, optical and transmission electron microscopy, and measurement of microhardness were used to study zirconium and Zr – Nb alloys loaded by spherical converging stress waves of different intensity. It is revealed that the phase and structural states of the specimens depend on the loading intensity, the niobium content and the depth of the layer in the sphere. The ω-phase (high pressure phase) is retained in a metastable state only after low-intensity loading, and the quantity of the ω-phase increases with increase in niobium content in the alloy. The ω-phase is not retained after high-intensity loading because of high remaining temperatures. It was established that various defects (deformation twins, dislocations, adiabatic shear bands, regions of unstable plastic flow and cracks) are produced during loading.