Abstract
The authors studied mobility of boundaries of planeβparallel twin layers in Inβ0.2 wt.% Pb and Inβ2 wt.% Pb crystals in the temperature range 290β373 K when stresses are applied Ο/G = (1.35 β 7) Γ 10^β6^ (G is the shear modulus). They found that lead concentration increase as well as dislocation structure deterioration result in lower boundary velocity for a constant stress.
In Inβ2 wt.% Pb crystals, the boundary velocity is well describable as V~n~ = V~0~(Ο) Γ Γ exp [ β Ξ__H__ (Ο)/kT] where V~0~(Ο) = Ae^Ξ±Ο/G^ (A = 10^β3^ cm/s, Ξ± = 1.1 Γ 10^6^) Ο Ξ__H__(Ο) is the activation energy depending on the stress, ranging under these circumstances from 0.33 to 0.43 eV.
At present it is difficult to interpret the results at hand. The analysis allows only to assume that the change in the boundary movement activation energy for impure crystals as against that for pure ones can be associated with the impurity effect on the structure of the intermediate zone between the twin and the matrix. The dependence of the preβexponential factor on the stress is probably due to the effect of the internal longβrange stress field on sources of twinning dislocations.
Comparison with data for calcite and pure indium shows that twin boundary mobility parameters and their dependence on the stress are governed by the crystal type and defect structure.