Studying Grain Boundary Strengthening by Dislocation-Based Strain Gradient Crystal Plasticity Coupled with a Multi-Phase-Field Model

Abstract

One ambitious objective of Integrated Computational Materials Engineering (ICME) is to shorten the materials development cycle by using computational materials simulation techniques at different length scales. In this regard, the most important aspects are the prediction of the microstructural evolution during material processing and the understanding of the contributions of microstructural features to the mechanical response of the materials. One possible solution to such a challenge is to apply the Phase Field (PF) method because it can predict the microstructural evolution under the influence of different internal or external stimuli, including deformation. To accomplish this, it is necessary to take into account plasticity or, specifically, non-homogeneous plastic deformation, which is particularly important for investigating the size effects in materials emerging at the micron length scale. In this work, we present quasi-2D simulations of plastic deformation in a face centred cubic system using a finite strain formulation. Our model consists of dislocation-based strain gradient crystal plasticity implemented into a PF code. We apply this model to study the influence of grain size on the mechanical behavior of polycrystals, which includes dislocation storage and annihilation. Furthermore, the initial state of the material before deformation is also considered. The results show that a dislocation-based strain gradient crystal plasticity model can capture the Hall-Petch effect in many aspects. The model reproduced the correct functional dependence of the flow stress of the polycrystal on grain size without assigning any special properties to the grain boundaries. However, the predicted Hall-Petch coefficients are significantly smaller than those found typically in experiments. In any case, we found a good qualitative agreement between our findings and experimental results.

Size Effect on Mechanical Properties and Deformation Behavior of Pure Copper Wires Considering Free Surface Grains

“…In the Taylor model [ 30 , 35 ], an upper bound model requires at least five active slip systems. while the lower bound model (the Schmid model), requires only one active slip system [ 1 ]. For FCC crystals, M is equal to 3.06 and 2.23 for the Taylor and Schmid modellings, respectively [ 14 , 36 ].…”

“…Plastic micro-forming technology has a wide application prospect in the fields of micro-mechatronics, bio-medicine and micro-energy due to its advantages of simple processing, high efficiency, low cost, excellent mechanical properties, and good repeatability. In plastic micro-forming technology, the size of the molded parts is less than 1 mm [ 1 , 2 , 3 , 4 ], with the crystal model ranged from single crystal to polycrystal. As a result of the size effect, the forming quality and basic properties of the miniature parts are changed [ 5 , 6 , 7 ].…”

Review of γ’ Rafting Behavior in Nickel-Based Superalloys: Crystal Plasticity and Phase-Field Simulation

“…Superalloys are generally multiphase and/or multicomponent materials, which require large number of field variables or physical quantities in the phase-field method in addition to mechanical deformation (elastic and elasto-plastic deformation). They provide a practical application of the phase-field theory in the understanding of the microstructure evolution of multiphase, polycrystal, and multicomponent materials [81]. The combination of the phase-field model and the crystal plasticity likely opens a new avenue for the study of the mechanical deformation and microstructure evolution of superalloys under concurrent action of thermal and mechanical loading.…”

Nonsingular Stress Distribution of Edge Dislocations near Zero-Traction Boundary

“…Otherwise, the nucleation and mobility of dislocations near the tip of a crack have a strong impact on the fracture mechanics of the material [ 7 ]. Furthermore, an in-depth understanding of dislocation dynamics and dislocation-induced elastic fields near traction-free boundaries [ 8 , 9 , 10 ] and grain boundaries [ 9 , 11 , 12 , 13 , 14 ], as well as the assessment of the boundary conditions used in the existing formulations [ 15 ] are critical to predicting the performance of advanced materials: they include gold nanowires [ 16 , 17 ], barium titanium nanomaterials [ 18 ], functionally graded materials [ 19 ], and other metallic and semiconductor materials [ 20 , 21 , 22 , 23 ].…”