Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates

Abstract

Alloying metals with other elements is often done to improve the material strength or hardness. A key microscopic mechanism is precipitation hardening, where precipitates impede dislocation motion, but the role of such obstacles in determining the nature of collective dislocation dynamics remains to be understood. Here, three-dimensional discrete dislocation dynamics simulations of FCC single crystals are performed with fully coherent spherical precipitates from zero precipitate density upto ${\rho }_p=10^{21}{\text{m}}^{-3}$ and at various dislocation-precipitate interaction strengths. When the dislocation-precipitate interactions do not play a major role the yielding is qualitatively as for pure crystals, i.e., dominated by "dislocation jamming", resulting in glassy dislocation dynamics exhibiting critical features at any stress value. We demonstrate that increasing the precipitate density and/or the dislocation-precipitate interaction strength creates a true yield or dislocation assembly depinning transition, with a critical yield stress. This is clearly visible in the statistics of dislocation avalanches observed when quasistatically ramping up the external stress, and is also manifested in the response of the system to constant applied stresses. The scaling of the yielding with precipitates is discussed in terms of the Bacon-Kocks-Scattergood relation.

7 pages, 5 figures. Submitted to Physical Review Materials

References in corpus (7)

• Machine learning plastic deformation of crystals
• Avalanches and Plastic Flow in Crystal Plasticity: An Overview
• Scaling Properties of Dislocation Simulations in the Similitude Regime
• Analysis of power-law exponents by maximum-likelihood maps
• Glassy features of crystal plasticity
• Excitation spectra in crystal plasticity
• Plastic strain is a mixture of avalanches and quasi-reversible deformations: Study of various sizes

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• Avalanche correlations and stress-strain curves in discrete dislocation plasticity