Kinetics of Plastic Deformation at Superconducting Transitions

Abstract

An analysis has been carried out of the influence of the superconducting (SN and NS) transitions on the kinetics and parameters of plastic deformation for the models of viscous and thermally activated dislocation motion.

Inertial mechanism of discontinuous plastic flow of lead in the superconducting state

“…Two experimental facts [21] are supportive of the inertial model: (i) a t sufficiently low temperatures, the ratio of the dislocation velocities in the normal (N) and the superconducting (S) states measured upon the N + S transition is significiantly larger than the corresponding ratio found upon the S + N transition; and (ii) the estimated magnitude of the average dislocation velocity, of the order of to 10-1 cm/s, appears to be too low for purely viscous motion. As indicated in [20], the kinetics of plastic flow at the superconducting transition do not contradict the inertial model.…”

Thermal activation analysis of dislocation motion in CdTe

“…l a ) . The plastic strain rate d can be expressed in terms of o(t) during dynainic loading [17] . S(d..,-d.)…”

Negative and positive photoplastic effect in CdTe

“…I n addition the ratio of the plastic strain rates in the illiiminated El (1 = light) and non-illuminated Bd (d = = dark) states a t t,lie instant of switching the light on a.nd off were ca~lcrilated from mcasurcd slope changes of t,he stress-strain ciirve. Indeed, the plastic, strain rate E can be expressed in terms of the following parameters of the stress-strain curve [14] where S is the cross-head speed, I the samplc length, b = dg/dt the slope of the stress-strain curve, the slope of the stress-strain curve in the elastic region (A = 0) a t the same S (see Fig. I).…”

“…By invest>igating the spectral and temperature dependence of the PPE, the nature and energetic levels of various defects influencing it can be analysed [l, 8,131. The PPE resulting from a change in dislocation mobility by illumination can be used as an additional technique for the determination of these parameters (similarly the stress change a t the superconducting transition has been used to test' models for dislocation niotion in P b at low temperature [14]).…”