The spatial distribution of shear bands was investigated in 304L stainless steel through the radial collapse of a thick-walled cylinder under high-strain-rate deformation (∼104 s−1). The shear-band initiation and propagation were also examined. Self-organization of multiple adiabatic shear bands was observed. The effect of grain size on spacing of shear bands was investigated at four different ...

A unified statistical dislocation-mediated crystal plasticity model is proposed to understand how the sample size affects yield strength of metals in different systems, namely, single crystals, columnar-grain structured thin films, and polycrystals. The takes into account randomness pre-existing dislocation network, grain orientation, predict as a function extrinsic (i.e. dimensions) intrinsic ...

Results on annealed nickel show that the total number of counts of both magnetic and acoustic Barkhausen signals vary inversely with grain size. In decarburized steels the total number of counts and the amplitude of both Barkhausen signals increase in proportion to grain size. The paper addresses these results in context of grain size, grain‐boundary segregation, and precipitate effect.

[1] Lithospheric shear localization, as occurs in the formation of tectonic plate boundaries, is often associated with diminished grain size (e.g., mylonites). Grain size reduction is typically attributed to dynamic recrystallization; however, theoretical models of shear localization arising from this hypothesis are problematic because (1) they require the simultaneous action of two creep mecha...

Focusing on nanocrystalline (nc) pure face-centered cubic metals, where systematic experimental data are available, this paper presents a brief overview of the recent progress made in improving mechanical properties of nc materials, and in quantitatively and mechanistically understanding the underlying mechanisms. The mechanical properties reviewed include strength, ductility, strain rate and t...

This work has two primary goals. The first is to advance our fundamental understanding of grain boundaries by making direct measurements of grain boundary thermodynamic properties using ultrafine-grained materials. The second is to explore possible deviations from conventional behavior at ultrafine grain sizes, specifically in regards to grain boundary thermodynamic properties and solute segreg...

A long-standing controversy exists between molecular dynamics simulations and experiments on the twinning propensity of nanocrystalline (NC) face-centered-cubic metals. For example, three-dimensional molecular dynamics simulations rarely observed twins in NC Ni, whereas experiments readily observed them. Here this discrepancy is resolved by experimental observation of an inverse grain-size effe...

in this study, the effect of grain size on nitrogen diffusion into ck45 has been investigated. in order to obtain different grain sizes, samples were annealed and normalized at various temperatures and durations.the grain size was determined with clemex vision software. then, the specimens were exposed to dc plasma nitriding treatment and again analyzed by optical microscope ,scanning electron ...

When a propagating cleavage front encounters a high-angle grain boundary it first penetrates through the grain boundary stably. With increasing penetration depth the resistance of the grain boundary rises, resulting in the well-known R-curve. When the balance between the rates of the energy release rate and the grain boundary resistance is reached, the crack advance becomes unstable and the gra...

We have studied the temperature dependence of low-field magnetoresistance and current-voltage characteristics of a low-angle bi-crystal grain boundary junction in perovskite manganite La2/3Sr1/3MnO3 thin film. By gradually trimming the junction we have been able to reveal the non-linear behavior of the latter. With the use of the relation MGB ∝ Mbulk √ MR we have extracted the grain boundary ma...