EFFECT OF QUENCHING ON THE DYNAMIC MECHANICAL PROPERTIES OF POLYCRYSTALLINE VANADIUM

The effect of quenching at high temperatures on the regularities of changes of the logarithmic decrement of the torsional oscillations damping and the dynamic shear modulus in the 10^-5-10^-3 interval of strain amplitude in polycrystalline vanadium has been studied. The critical values of the strain amplitude, at which the dislocations segments begin to breakaway from the weak and strong pinning centers have been determined. After short annealing (20 min.) at fixed tempertures of 700 and 900° C and subsequent quenching at room temperture a decrease of impurity concentration in Cottrell atmosphere around the dislocations is achieved. These changes led to a significant reduction of the critical strain amplitude of dislocations blocking and the dynamic shear modulus, and a strong increase in the intensity of energy absorption in a wide range of oscillations amplitudes. The concentration changes of the Cottrell atmosphere around the dislocations led to the formation of several  values of elastic limits. The obtained results reveal the possibilities of changing the mobility of the dislocation structure by quenching from high temperatures, which is the basis for controlling of the mechanical properties of vanadium.