Ab initiotensile tests of Al bulk crystals and grain boundaries: Universality of mechanical behavior

Abstract

We have performed ab initio tensile tests of bulk Al along different tensile axes, as well as perpendicular to different grain boundaries to determine mechanical properties such as interface energy, work of separation and theoretical strength. We show that all the different investigated geometries exhibit energy-displacement curves that can be brought into coincidence in the spirit of the well known universal binding energy relationship curve. This simplifies significantly the calculation of ab initio tensile strengths for the whole parameter space of grain boundaries.

Ab Initio Study of the Combined Effects of Alloying Elements and H on Grain Boundary Cohesion in Ferritic Steels

“…The supercells were compressed and expanded along [310] up to the free surface energy, and the universal binding energy relationship (UBER) [40] was fitted to the data. The critical stress for fracture (fracture stress σ f ) is the first derivative at the displacement at the point of inflection (where the curvature is zero) [6,39,41].…”

Cohesive stress heterogeneities and the transition from intrinsic ductility to brittleness

“…6d), involving self interstitial injection, but also local glide in between the cavities. The energetics is completely different from the cleavage case [42]. The W sep values are coherent with [40] which finds 6 J/m 2 for a brittle orientation (without initial cavities).…”

“…Combined to δ(y), gives the shape of the σ CZ (δ(y), y) relation. The data is noisy, but, at low loads, when the process zone is small, σ CZ (δ) seems to follow the universal binding law of Rose [42] (for a precise determination of cohesive zone relations from atomistics see [43]). At higher loads, σ CZ (δ) seems linear.…”

Criteria of instability of copper and aluminium perfect crystals subjected to elastic deformation in the temperature range 0 – 400 K

“…In the first works dedicated to this problem, the main goal was to determine the theoretical strength [14]. Nowadays, the research is focused on the failure of nanocrystals at applied stress below the theoretical limit, the possible reasons being the effect of twins and grain boundaries [15,16] or the sample crystallographic orientation with respect to the loading direction [17 -20]. The effect of compression and tension on the theoretical strength of covalent crystals was also studied [21][22][23].…”