Mapping pure plastic strains against locally applied stress: Revealing toughening plasticity

The deformation of all materials can be separated into elastic and plastic parts. Measuring the purely plastic component is complex but crucial to fully characterize, understand, and engineer structural materials to bend, not break. Our approach has mapped this to answer the long-standing riddle in materials mechanics: The low toughness of body-centered cubic metals, where we advance an experimentally led mitigative theory. At a micromechanically loaded crack, we measured in situ the stress state applied locally on slip systems, and the dislocation content, and then correlatively compared with the occurrence-or not-of toughness-inducing local plasticity. We highlight limitations and potential misinterpretations of commonly used postmortem transmission electron imaging. This should enable better-informed design for beneficial plasticity and strength in crystalline and amorphous solids alike.

Automated summary

This article discusses the separation of material deformation into elastic and plastic parts, emphasizing the importance of measuring the purely plastic component for understanding and designing structural materials. The study addresses the low toughness issue of body-centered cubic metals and proposes a mitigative theory. The limitations and potential misinterpretations of common postmortem transmission electron imaging are highlighted.