The Experts below are selected from a list of 84 Experts worldwide ranked by ideXlab platform
Peter W Chung - One of the best experts on this subject based on the ideXlab platform.
-
binary Dislocation Junction formation and strength in hexagonal close packed crystals
International Journal of Plasticity, 2016Co-Authors: Chi Chin Wu, Sylvie Aubry, A Arsenlis, Peter W ChungAbstract:Abstract This work examines binary Dislocation interactions, Junction formation and Junction strengths in hexagonal close-packed ( hcp ) crystals. Through a line-tension model and Dislocation dynamics (DD) simulations, the interaction and dissociation of different sets of binary Junctions are investigated involving one Dislocation on the ( 01 1 ¯ 0 ) prismatic plane and a second Dislocation on one of the following planes: (0001) basal, ( 1 1 ¯ 00 ) prismatic, ( 1 1 ¯ 01 ) primary pyramidal, or ( 2 ¯ 112 ) secondary pyramidal. Varying pairs of Burgers vectors are chosen from among the common types: the basal type a > : 1 3 11 2 ¯ 0 > , prismatic type c >: , and pyramidal type a + c > : 1 3 11 2 ¯ 3 ¯ > . For binary interaction due to Dislocation intersection, both the analytical results and DD-simulations indicate a relationship between symmetry of interaction maps and the relative magnitude of the Burgers vectors that constitute the Junction. Using analytical formulae, a simple regressive model is also developed to represent the Junction yield surface. The equation is treated as a degenerated super elliptical equation to quantify the aspect ratio and tilting angle. The results provide analytical insights on binary Dislocation interactions that may occur in general hcp metals.
Chi Chin Wu - One of the best experts on this subject based on the ideXlab platform.
-
binary Dislocation Junction formation and strength in hexagonal close packed crystals
International Journal of Plasticity, 2016Co-Authors: Chi Chin Wu, Sylvie Aubry, A Arsenlis, Peter W ChungAbstract:Abstract This work examines binary Dislocation interactions, Junction formation and Junction strengths in hexagonal close-packed ( hcp ) crystals. Through a line-tension model and Dislocation dynamics (DD) simulations, the interaction and dissociation of different sets of binary Junctions are investigated involving one Dislocation on the ( 01 1 ¯ 0 ) prismatic plane and a second Dislocation on one of the following planes: (0001) basal, ( 1 1 ¯ 00 ) prismatic, ( 1 1 ¯ 01 ) primary pyramidal, or ( 2 ¯ 112 ) secondary pyramidal. Varying pairs of Burgers vectors are chosen from among the common types: the basal type a > : 1 3 11 2 ¯ 0 > , prismatic type c >: , and pyramidal type a + c > : 1 3 11 2 ¯ 3 ¯ > . For binary interaction due to Dislocation intersection, both the analytical results and DD-simulations indicate a relationship between symmetry of interaction maps and the relative magnitude of the Burgers vectors that constitute the Junction. Using analytical formulae, a simple regressive model is also developed to represent the Junction yield surface. The equation is treated as a degenerated super elliptical equation to quantify the aspect ratio and tilting angle. The results provide analytical insights on binary Dislocation interactions that may occur in general hcp metals.
-
Dislocation Dynamics Simulations of Junctions in Hexagonal Close-Packed Crystals
MRS Proceedings, 2012Co-Authors: Chi Chin Wu, Sylvie Aubry, Peter C. Chung, Athanasios ArsenlisAbstract:ABSTRACTThe formation and strength of Dislocations in the hexagonal closed-packed material are studied through Dislocation Junctions and the critical stress required to completely break them. Dislocation dynamics calculations of Junctions are compared to an analytical line tension approximation in order to verify the simulations. Results show agreements between the models. Also the critical shear stress necessary to break a short and a long Dislocation Junction is computed numerically. Unzipping envelopes are mapped out for these Junctions to describe their stability regions as functions of resolved shear stresses on the glide planes. The example of two non-coplanar binary Dislocation Junctions with slip systems [2 -1 -1 0] (0 1 -1 0) and [-1 2 -1 0] (0 0 0 1) corresponding to a prismatic and basal slip respectively is chosen to verify and validate our implementation.
Sylvie Aubry - One of the best experts on this subject based on the ideXlab platform.
-
binary Dislocation Junction formation and strength in hexagonal close packed crystals
International Journal of Plasticity, 2016Co-Authors: Chi Chin Wu, Sylvie Aubry, A Arsenlis, Peter W ChungAbstract:Abstract This work examines binary Dislocation interactions, Junction formation and Junction strengths in hexagonal close-packed ( hcp ) crystals. Through a line-tension model and Dislocation dynamics (DD) simulations, the interaction and dissociation of different sets of binary Junctions are investigated involving one Dislocation on the ( 01 1 ¯ 0 ) prismatic plane and a second Dislocation on one of the following planes: (0001) basal, ( 1 1 ¯ 00 ) prismatic, ( 1 1 ¯ 01 ) primary pyramidal, or ( 2 ¯ 112 ) secondary pyramidal. Varying pairs of Burgers vectors are chosen from among the common types: the basal type a > : 1 3 11 2 ¯ 0 > , prismatic type c >: , and pyramidal type a + c > : 1 3 11 2 ¯ 3 ¯ > . For binary interaction due to Dislocation intersection, both the analytical results and DD-simulations indicate a relationship between symmetry of interaction maps and the relative magnitude of the Burgers vectors that constitute the Junction. Using analytical formulae, a simple regressive model is also developed to represent the Junction yield surface. The equation is treated as a degenerated super elliptical equation to quantify the aspect ratio and tilting angle. The results provide analytical insights on binary Dislocation interactions that may occur in general hcp metals.
-
Dislocation Dynamics Simulations of Junctions in Hexagonal Close-Packed Crystals
MRS Proceedings, 2012Co-Authors: Chi Chin Wu, Sylvie Aubry, Peter C. Chung, Athanasios ArsenlisAbstract:ABSTRACTThe formation and strength of Dislocations in the hexagonal closed-packed material are studied through Dislocation Junctions and the critical stress required to completely break them. Dislocation dynamics calculations of Junctions are compared to an analytical line tension approximation in order to verify the simulations. Results show agreements between the models. Also the critical shear stress necessary to break a short and a long Dislocation Junction is computed numerically. Unzipping envelopes are mapped out for these Junctions to describe their stability regions as functions of resolved shear stresses on the glide planes. The example of two non-coplanar binary Dislocation Junctions with slip systems [2 -1 -1 0] (0 1 -1 0) and [-1 2 -1 0] (0 0 0 1) corresponding to a prismatic and basal slip respectively is chosen to verify and validate our implementation.
S B Biner - One of the best experts on this subject based on the ideXlab platform.
-
solute and Dislocation Junction interactions
Acta Materialia, 2008Co-Authors: Q Chen, S B BinerAbstract:In this study, the role of solute segregation on the strength and the evolution behavior of Dislocation Junctions is studied by utilizing kinetic Monte Carlo and three-dimensional Dislocation dynamics simulations. The different solute concentrations and the character of the Junctions are all included in the simulations in an effort to make a parametric investigation. The results indicate that the solutes have a profound effect on the strength of the Junctions. Solute segregation can lead to both strengthening and weakening behavior, depending upon the evolution of the Dislocation Junctions. The local solute concentration seems to be the more relevant parameter to characterizing the solute and Dislocation interactions, due to the short-range stress field of solutes; and its bounds are set by the unconstrained volume dilatation.
Laurent Capolungo - One of the best experts on this subject based on the ideXlab platform.
-
Mechanism-based modeling of solute strengthening: Application to thermal creep in Zr alloy
International Journal of Plasticity, 2018Co-Authors: Laurent Capolungo, Carlos N. ToméAbstract:Abstract In this work, a crystallographic thermal creep model is proposed for Zr alloys that accounts for the hardening contribution of solutes via their time-dependent pinning effect on Dislocations. The core-diffusion model proposed by Soare and Curtin (2008a) is coupled with a recently proposed constitutive modeling framework (Wang et al., 2017, 2016) accounting for the heterogeneous distribution of internal stresses within grains. The Coble creep mechanism is also included. This model is, in turn, embedded in the effective medium crystallographic VPSC framework and used to predict creep strain evolution of polycrystals under different temperature and stress conditions. The simulation results reproduce the experimental creep data for Zircaloy-4 and the transition between the low (n∼1), intermediate (n∼4) and high (n∼9) power law creep regimes. This is achieved through the dependence on local aging time of the solute-Dislocation binding energy. The anomalies in strain rate sensitivity (SRS) are discussed in terms of core-diffusion effects on Dislocation Junction strength. The mechanism-based model captures the primary and secondary creep regimes results reported by Kombaiah and Murty (2015a, 2015b) for a comprehensive set of testing conditions covering the 500–600 °C interval, stresses spanning 14–156 MPa, and steady state creep rates varying between 1.5·10−9s−1 to 2·10−3s−1. There are two major advantages to this model with respect to more empirical ones used as constitutive laws for describing thermal creep of cladding: 1) specific dependences on the nature of solutes and their concentrations are explicitly accounted for; 2) accident conditions in reactors, such as RIA and LOCA, usually take place in short times, and deformation takes place in the primary, not the steady-state creep stage. As a consequence, a model that accounts for the evolution with time of microstructure is more reliable for this kind of simulation.
-
Dislocation Junction formation and strength in magnesium
Acta Materialia, 2011Co-Authors: Laurent CapolungoAbstract:Abstract Adaptative meshing finite-element-based discrete Dislocation dynamics simulations are employed to predict Dislocation Junction formation in magnesium as well as their resulting strength. Apart from coplanar and collinear interactions, all possible interactions between basal, prismatic and pyramidal slip are considered. Among others it is found that while non-coplanar prismatic Junctions are more likely than basal–prismatic Junctions, the latter are more stable. However, pyramidal–prismatic Junctions appear more stable than pyramidal–basal Junctions. Finally, non-coplanar pyramidal Junctions are more likely than any other Junction formation, and these Junctions also appear to be amongst the strongest.