Overdriven dislocation-precipitate interactions at elevated temperatures in aluminum

TL;DR

This study uses a modified dislocation dynamics model to analyze dislocation-precipitate interactions at high temperatures in aluminum, revealing that dislocation bypassing and shearing are significant factors affecting deformation.

Contribution

It introduces a model that accounts for shearable and non-shearable precipitates in high-temperature dislocation dynamics simulations.

Findings

Dislocation interaction time increases with temperature.

Critical shear stress decreases at higher temperatures.

Thermal activation energy ratio remains below 0.15.

Abstract

The two-dimensional dislocation dynamics approach has been recently used for analyzing plastic deformation in metals and alloys at elevated temperatures. The two-dimensional approach, however, only accounts for the dislocation climbing process, and it assumes that dislocation bypassing and shearing of precipitates are negligible. To examine the validity of this assumption, this study quantifies dislocation bypassing and shearing of precipitates in terms of critical resolved shear stress, interaction time, and thermal activation energy for various precipitate strength levels, temperatures, and precipitate spacings. This study uses a modified dislocation dynamics approach that accounts for shearable and non-shearable precipitates. Simulations focus on the overdriven dislocation dynamics regime wherein the climbing process is limited by fast interactions between dislocations and precipitates. The results show that even though the resolved shear stress level required for a dislocation to overcome an array of precipitates decreases at higher temperatures, the interaction time between the dislocation and the precipitates increases. In addition, the maximum ratio of thermal activation energy to the precipitate energy barrier is only 0.15.