Jan 19, 2015 | No Comments | By Jessica Ader
Size-affected dislocation-mediated plasticity is important in a wide range of materials and technologies. The question of how to explain and predict the effect of size on the properties and response of materials has been at the forefront of mechanics and materials research. In a recent article in Nature Communications, HEMI Professor Jaafar A. El-Awady addresses this by developing an experimentally validated generalized size-dependent dislocation-based model from discrete dislocation dynamics simulations. The model is shown to predict the single and polycrystalline strength as a function of crystal/grain size and the dislocation density. In the article titled “Unravelling the physics of size-dependent dislocation-mediated plasticity”, Prof. El-Awady also developed a new deformation mechanism map for single crystals based on these simulations.
This work presents a micro-mechanistic framework to predict and interpret strength size-scale effects, and provides an avenue towards performing multiscale simulations without ad hoc assumptions. Because of the applicability of the model to an extremely large set of crystal/grain sizes (that is, bulk to tens of nanometers) and its portability for predicting the strength of both single and polycrystals, the proposed model is expected to have further applications in constitutive law development and multiscale methods. This model can also be extended to address problems where the high strain rate sensitivity of mobile dislocation density is important.