Modeling And Simulation Of Dislocation Dynamics For Nickel Based Sigle Crystaline Alloy

In the research field of material deformation,dislocation dynamics is being studied for its direct reflection of the relationship between material mechanical properties and dislocation activities such as dislocation multiplication,annihilation,the interaction between dislocations and between dislocation and solute atoms or precipitations.The microstructure of Nickel based single crystal alloy is mainly composed of the matrix phase and the precipitation phase,in which the cubic precipitation phase with L12 structure is regular and co lattice embedded in the FCC nickel matrix phase,which forms the so-called "mosaic" structure.This is the main feature of the structure of Nickel based single crystal alloy.In this paper,the 2 dimensional discrete dislocation dynamics is used to simulate the interaction between dislocations and between dislocation and the precipitates in the nickel based alloy,and the velocity and density of dislocations is used to obtain the stress-strain curve of nickel based alloy,and the relationship between strength and the microscopic parameters is analyze.The main work is as follows:(1)A two dimensional discrete dislocation dynamics model was built for nickel based alloy,containing the calculation of forces on dislocations,the movement of dislocations,the periodic boundary condition of the simulation zone and the interaction between dislocation and precipitations,etc.(2)Based on Microsoft Visual Studio platform,using C language,a program is designed for the two-dimensional discrete dislocation dynamics model,including the influence of all the microscopic factors in the model,and mostly focus on the analysis of behavior of dislocations cutting through precipitates and the motion of dislocations in the precipitation.(3)Reveal the relationship between mechanical properties and microstructure of nickel base alloy by control the shape,size,volume percentage of the precipitates and the antiphase boundary energy(APB energy).(4)According to the results of the simulation,the strength of nickel based alloy is influenced by the volume fraction and size of the precipitates and antiphase boundary energy.The strength of nickel based alloy is rise with the rise of the volume fraction of the precipitation,and is more allergic to the change of the precipitation at a higher volume fraction.The larger APB energy and smaller size of precipitate are also able to improve deformation resistance of Nickel-base single crystal superalloy.