Stress-induced ordering of interstitial atoms due to dislocation motion

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Abstract
The variation of the activation energy of plastic deformation with strain rate was investigated in iron-carbon alloys as a function of interstitial concentration, pre-strain, temperature and grain size. The activation energy was measured directly by a differential temperature technique and was found to be 12 to 14 kcal/mole a t fast strain rates, rising to 20 kcal/mole a t slower strain rates. The stress dependence of strain rate was investigated in two strain rate ranges and was found to be a linear function in the slow strain rate range and a logarithmic function in the fast strain rate range. It was concluded from the data that this investigation was a direct verification of theories of Schoeck and Seeger and Eshelby of stress-induced ordering of interstitial atoms due to the stress fields of moving dislocations. The observed minimum in the activation energy versus strain rate relationship proves that the activation energy of the usual low-temperature rate-controlling mechanism does not increase to 20 kcal/mole at zero effective stress and that under more usual methods of testing interstitial atoms do not affect the motion of dislocations.