Papers by Keyword: Structural Superplasticity

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Authors: Sriharsha Sripathi, K. Anantha Padmanabhan
Abstract: Structural superplasticity is observed in materials of different classes with μm–, sub–μm– or nm– grain size. In all cases mesoscopic grain/interphase boundary sliding (~ grain diameter or more) is suggested to be the rate controlling mechanism. Sub–μm grained metallic and ceramic systems are analyzed here and good agreement with experimental results is established. Compared with earlier works, the numerical procedure is more robust and the free energy of activation for the rate controlling process is matched with the value for the same obtained using Eshelby’s equation.
Authors: Young Won Chang
Abstract: An internal variable theory has been proposed to account for the essential microstructures during inelastic deformation. The framework of the theory is built on the basis of well known dislocation dynamics to provide the concept of an internal strain tensor as the most fundamental deformation state variable. The plastic and inelastic strain rate tensors are then naturally defined and also a kinematics relation among them can further be derived from the time rate of change of this internal strain tensor, which in fact accounts for the evolution of microstructures during inelastic deformation. To complete the theory, the constitutive relations between the various stress variables and their conjugate deformation rate variables are then derived based on the dislocation kinetics. The theory is then further extended to describe the structural superplasticity, taking this slip zone model with dislocation pile-ups as the major accommodation mechanism for grain boundary sliding. The experimental results obtained from the various crystalline materials are then presented and compared with each other in relation to the internal variable theory for inelastic deformation.
Authors: Tae Kwon Ha, Yong Nam Kwon, Young Won Chang
Authors: Jin Hwa Song, Hyun Tae Lim, Tae Kwon Ha, Young Won Chang
Authors: Tae Kwon Ha, Young Won Chang
Authors: Petr V. Trusov, Alexey I. Shveykin, Elvira R. Sharifullina, Nikita S. Kondratev
Abstract: The paper deals with three-level model of polycrystal inelasticity based on crystal plasticity. This model allows to regard the most important inelastic deformation mechanisms of polycrystals including grain boundary sliding. The inflow of intragranular dislocations, changing of the boundary structure under realization of grain boundary sliding and diffusion processes are taken into account in equations for grain boundary sliding. Consistency conditions of constitutive relations at the different scale levels are used in constructing model. The results of computational experiments under uniaxial tension of a representative volume are obtained with developed model. The results show that grain boundary sliding is important and must be taking into account.
Authors: Juan Daniel Muñoz-Andrade, A. Mendoza-Allende, J.A. Montemayor-Aldrete
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