Plastic behavior of fcc metals over a wide range of strain: Macroscopic and microscopic descriptions and their relationship

The room temperature macroscopic and microscopic plastic behavior of four face-centered cubic metals (Al, Au, Cu and Ni) is investigated experimentally over a wide strain range, and theoretical modeling is used to simulate the established major micromechanisms describing the evolution of mobile and forest dislocations during plastic flow. It is shown that forest dislocations develop primarily due to interaction between mobile dislocations, while the contribution from forest–mobile interactions is only minor. The trapping of mobile dislocations and the annihilation of forest dislocations are both controlled by the same thermally activated dislocation motion. These observations permit a simplification of the theoretical model that leads to an analytical relationship for the evolution of the total dislocation density as a function of strain. From this analysis, correlations are drawn between the macroscopic parameters describing the stress–strain relationship and the fundamental characteristics of the microscopic processes.