Karaseva E. Creep of transitive metals and alloys Zr, Hf Zr1Nb, Nb, NbТі in various structural states

Object: mechanisms of plastic deformation of Zr, Hf, Zr1Nb, Nb, NbTi in the creep regime, which determine their strength properties and thermomechanical stability. The purpose: determination of features of creep of metals and alloys with the hcp and bcc lattice (Zr, Hf, Zr1Nb, Nb, NbTi) in the temperature range 1,5-700 K in different structural states formed using intensive plastic deformation and heat treatment, determination of the mechanisms and types of stoppers which control the plastic flow of materials during creep. Methods: methods of active stretching and creep, methods of electron and optical microscopy, X-ray analysis, the resistive method and the measurement of thermoelectric power, thermal activation analysis. Results: it is determined that in the temperature range 1,5-140 K at strain rate 10-3s-1 for zirconium with a grain size of 100 microns oscillations of the yield stress caused by a change in the type of barriers controlling the plastic flow in this temperature range as well as changes in the conditions of dislocations are typical. It is determined that for fine-grained and fragments structures of Zr, Hf Zr1Nb, Nb, NbТі the large creep speed is the characteristic at relatively low temperatures (300 К). That corresponds to the degree law of deformation dependence epsilon ~ t1/3 and is a result of combined action the processes of hardening and return. Field of application: physics of solid state, physics of strength and plasticity