ICCM Conferences, The 8th International Conference on Computational Methods (ICCM2017)

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The DCM Simulations of the Matrix Dislocation Gliding through the Matrix Channel under the Influence of the Interfacial Dislocation Network
huang song

Last modified: 2017-07-06

Abstract


The discrete-continues model (DCM), a discrete dislocation dynamic (DDD) and finite element method (FEM) coupled simulation method, was used to investigate the influence of edge character interfacial dislocation network at the two-phase interfaces of the nickel-based superalloy on the gliding process of the matrix dislocation from one matrix channel to another matrix channel. An enhanced DCM algorithm is used comparing to the classical DCM to obtain more accurate stress field in a short distance near the dislocation core. The process of the matrix dislocation with different Burgers vector called D1, D2 and D3 gliding from one channel to another channel is studied. Such a gliding process can be deposed into two steps. In the first step, the matrix dislocation is in one matrix channel and going to bow into another matrix channel. After the matrix dislocation bow into the matrix channel completely, the matrix dislocation transfers from bowing to gliding along the matrix channel which is considered to be the second step. If the matrix dislocation bowing into the channel completely, the current configuration is the critical configuration of matrix dislocation entering the channel and if one of the matrix dislocation segments in the channel gliding out the channel for the first time, the current configuration is considered to be the critical configuration of matrix dislocation gliding out the channel. The critical stress of the two critical configurations is investigated. If the depositing trailing arm of the matrix dislocation is screw character dislocation, the interfacial dislocation networks have a weak influence on the critical stress of the matrix entering and gliding out the matrix channel. If the depositing trailing arm of the matrix dislocation is mix character dislocation, the interfacial dislocation network will hinder the matrix dislocation from entering and gliding through the matrix channel remarkably. After the matrix dislocation enter the matrix channel completely, addition applied load is need to push the matrix dislocation glide through the matrix channel. And we found that as the channel width become narrower the addition applied load is not increased much for the condition without interfacial dislocation network while accounting for interfacial dislocation network the addition applied load is significantly increased. The critical stress is quantitatively studied with different dislocation spacing of interfacial dislocation network and we found that the influence of the interfacial dislocation network is proportional to the lattice mismatch of the nickel-based superalloy with a certain channel width.And an equation is proposed to describe the relation of critical stress and channel width with the influence of interfacial dislocation network. In addition the dislocation dissociation in dislocation bowing in the matrix channel is investigated. The matrix dislocation is more easily to dissociate whether the interfacial dislocation network is considered or not in narrower channel with low stacking fault energy and the direction of applied load and the matrix channel will influence the dissociation of the leading and trailing partial dislocation and we found that in some condition the matrix dislocation is always trend to dissociate to glide through the matrix channel with interfacial dislocation network.

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