Microstructure-dependent local strain behavior in polycrystals through in situ scanning electron microscope tensile experiments

TL;DR

This study uses in situ SEM tensile experiments combined with EBSD to analyze how microstructure influences local strain behavior in polycrystals, revealing that grain boundaries and triple junctions accumulate plasticity near yield.

Contribution

It introduces a method integrating digital image correlation with EBSD to analyze microstructure-dependent local strain in polycrystals during tensile testing.

Findings

Maximum shear strain increases with Schmid factor.

Strain extremes are higher near grain boundaries.

Plasticity accumulates at grain boundaries and triple junctions.

Abstract

Digital image correlation of laser-ablated platinum nanoparticles on the surface of a polycrystalline metal (nickel-based superalloy Rene 88DT) was used to obtain the local strain behavior from an in situ scanning electron microscope tensile experiment at room temperature. By fusing this information with crystallographic orientations from EBSD, a subsequent analysis shows that the average maximum shear strain tends to increase with increasing Schmid factor. Additionally, the range of the extreme values for the maximum shear strain also increases closer to the grain boundary, signifying that grain boundaries and triple junctions accumulate plasticity at strains just beyond yield in polycrystalline Rene 88DT. In situ experiments illuminating microstructure-property relationships of this ilk may be important for understanding damage nucleation in polycrystalline metals at high temperatures.