Deformation mechanisms in ultrafine-grained metals with an emphasis on the Hall–Petch relationship and strain rate sensitivity

Year: 2021

Type: article

Abstract: Ultrafine-grained materials display almost no strain hardening, an enhanced strain rate sensitivity and grain boundary offsets during plastic deformation. It is expected that dislocation climb is active in order to enable prompt recovery. The present analysis proposes a deformation mechanism that includes these effects and follows from the mechanism for high temperature grain boundary sliding. This mechanism predicts the relationship between strain rate, flow stress, grain size, temperature and basic material properties such as the Burgers vector modulus, the shear modulus and the grain boundary diffusion coefficient. The model may be used to estimate the final grain size achieved by severe plastic deformation and the strain rate sensitivity. An analysis shows that the predicted behavior agrees with the data from multiple experimental investigations and provides a good estimate of the Hall–Petch slope for different materials which includes breakdown and inverse Hall–Petch behavior under some conditions. The incorporation of a threshold stress provides an opportunity to predict the relationship between flow stress and grain size for a broad range of grain sizes, strain rates and temperatures. An excellent agreement is observed between the predictions of the model and experimental data for Al, Cu, Fe (α), Fe(γ), Mg, Ni, Ti and Zn.

Source: Journal of Materials Research and Technology

DOI: 10.1016/j.jmrt.2021.06.016

Authors: Roberto B. Figueiredo, Terence G. Langdon

Institutions: Universidade Federal de Minas Gerais, University of Southampton

Language: English

Topic: Microstructure and mechanical properties

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,100

Funders: Stowers Institute for Medical Research, National Natural Science Foundation of China, Chongqing University, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Instituto Serrapilheira, European Research Council, National Key Research and Development Program of China, Division of Materials Research, H2020 European Research Council

OpenAlex ID: W3174864946