Bringing Together Computational and Experimental Capabilities at the Crystal Scale

Abstract

Many phenomena of interest occur at the scale of crystals or are controlled be events happening at the crystalline scale. Examples include allotropic phase transformations in metals and pore collapse in energetic crystals. The research community is increasingly able to make detailed experimental observations at the crystalline scale and to inform crystal scale models using lower length scale computational tools. In situ diffraction techniques are pushing toward finer spatial and temporal resolution. Molecular and dislocation dynamics calculations are now able to directly inform mechanisms at the crystalline scale. Taken together, these factors give crystal based continuum models the ability to rationalize experimental observations, investigate competition among physical processes, and, when appropriately formulated and calibrated, predict behaviors. We will present an overview of current efforts, with emphasis on recent work investigating phase transformations and twinning in metals.

A polycrystal plasticity model of strain localization in irradiated iron

“…6(b) we see that the early strain localizations are cooperative across several grains. This is somewhat similar to the modeling observation that large-volume phase transformations proceed cooperatively across several grains (Barton et al, 2005(Barton et al, , 2009c. Comparing Fig.…”

The use of discrete harmonics in direct multi-scale embedding of polycrystal plasticity

“…(13), these fields then determine the updated harmonic coefficients appearing as part of H + in the output of Eq. (24). Thus for VPSC there is a fairly complete and complex coupling between the inputs and outputs to Eq.…”

“…Thus for VPSC there is a fairly complete and complex coupling between the inputs and outputs to Eq. (24). When using the Taylor linking assumption in Section 4 (and above in Section 2), we employ three types of slip systems: basal {0001}⟨1210⟩, prismatic {1010}⟨1210⟩, and pyramidal ⟨c+a⟩ slip {1011}⟨1123⟩.…”

“…For now we employ Eqs. (23) and (24) to demonstrate the approach with a comparatively simple formulation. While the implicit solve of Eq.…”

“…Evolution of the texture, especially for materials that exhibit mechanical twinning, can significantly affect the evolution of flow stress at moderate levels of plastic deformation. It is worth noting that models to directly capture twin domain formation typically require fine computational grids and significant computational expense [24]. While there is utility in studies focused on details of twin formation, the focus here is on capturing the gross effects of texture evolution and twin formation on flow stress evolution.…”