โ Scribed by A.S. Krausz
No coin nor oath required. For personal study only.
The direct and indirect methods of dislocation velocity (v) measurements usually lead to the empirical expression ti cc 7% or v cc exp (-C/T) where 7 is the stress and 12, c are experimental constants. It is shown that the dislocation velocity can be described in terms of physical concepts by using the rate theory model of the asymmetrical energy barrier and assuming that the activation energy of the rate controlling process is linearly dependent on the skess. The equation obtained describes well the dislocation velocity in LiF, Ge, Si,InSb, GaSb, N&I, Fe-Si, Ni, W, Zr, Pb, and in ice. An interpretation of the stress exponent *)i was also obtained in terms of the size and the shape of the energy barrier. This expression can be directly related to t.he yieId drop and delay t,ime phenomena. THEORIE DE LA VITESSE DE DEPLACEMENT DES DISLOCATIONS Les methodes dire&es et indirectes de mesures de la vitesse des dislocations (v) eonduisent habituellement k I'expression empiriquo 2) cc 7" ou w a exp (~ C/T) oh rest la contrainte et n, c sont des constantes experimentales. L'auteur montre que la vitesse de deplaoement de la dislocation peut etre d&crib a l'aide de concepts physiques en utilisant le modele de la barriere d'energie asymetrique et en supposant que l'energie d'aotivation du processus contr8lant la vitesse depend linea,irement de la oontrainte. L'eyuation obtenue dirorit bien la vitesse de deplacement des dislocations
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