Discussion: Activation volumes of plastic deformation of crystals. (15th March 2018)

• Record Type: Journal Article
• Authors: Blum, W.
• Is Part Of: Scripta materialia. Number 146(2018)
• Page Start: 27
• Page End: 30
• Publication Date: 2018-03-15
• Subjects: Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2017.10.029
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: Two data sets reporting apparent activation volumes V app of plastic deformation of ultrafine-grained Cu are compared. They differ strongly in magnitude and stress dependence of V app . It is suggested that the difference results from differences in testing method. While V app from stress relaxations appears to be consistent with expectations for the activation of thermally activated glide of dislocations in the bulk of the material, V app from rate change tests appears to characterize the quasi-stationary deformation where dynamic recovery plays a major role. This underscores the necessity to specify which of the various thermally activated subprocesses of deformation are tested. Graphical Abstract: Apparent activation volumes of UFG Cu as function of stress σ normalized by the shear modulus G(T) [4] from stress relaxations of Isaev et al. [2] with data from [5], (b) from rate change tests of Duhamel et al. [1] (filled circles);with datum from Wang and Ma (cryo-rolled Cu) [10] and data set of Blum et al. [6] (dash-dotted, 24 passes of equal channel angular pressing); dashed line for grain size d=6 ×10 −7 m in units of b .