Phase Simulation Of Dendritic Growth Of Al-Cu Binary Single Phase Alloy

The methods for numerical simulation of microstructure are mainly:the deterministic method, stochastic method and the phase field method. Of which:deterministic method based on distribution of temperature field from a macro point of view to solid-liquid partitioning. The phase field method based on that the total energy of system always tends to the minimum value, the entropy functional variation tends to zero. In the description of nonequilibrium evolution of the complex phase interface, need not keep track of the complex solid-liquid interface, can realize the complex topography simulation in metal dendrite growth. The numerical simulation of the microstructure of the metal materials is of great significance, but also one of the main development direction on application of computer in the field of material science.This paper first reviews the development of the phase field theory models. The phase field model based on a sharp interface model, then pointed out the basic idea of the phase field method. The phase field method by introducing the phase field variable, the sharp interface into a diffusion type interface, according to set up the control equation unified basic law Ginzburg-Landau theory and thermodynamics. Analysis and processing of simulation theory is based on the calculation。 In this paper, the phase field variable diffusion models of dendrite growths of pure aluminum and aluminum two alloy were introduced. The models through the conduction equation of free enthalpy of establish the diffusion model can explain the nature of the solid fraction. There is a corresponding relationship between solid phase rate diffusion model of this, and all kinds of metal and alloy diffusion between quantitative phase field equations can be established. The phase field model obtained can be used to simulate the dendrite growth in isothermal condition, can also be used to simulate the non-isothermal conditions. Solid phase rate of change will also be affected by the physical quantity and the entropy. For example, growth velocity, sub cooling etc.Application of this research and numerical model, the physical meaning of the phase field simulation calculation method and the simulation of solidification microstructures are explored. And using the phase field simulation method, for solving the Al-4.5%Cu equiaxed dendrite growth process.The thesis also studies the mesh size, anisotropy and random disturbance effects on the simulation results, the values of these key parameters.The governing equation is discretized finite difference based on homogeneous grid separation, in order to save time, temperature control equation with explicit algorithm, reduce the amount of computation, improve the computational efficiency. In order to visually display of the simulation results, the visualization of solidification simulation, calculation method of some important parameters in the dendritic growth are put forward. Visualization software system of MFC microstructure simulation results is developed based on, can realize the simulation results show the vivid image, and can easily realize the integration and various numerical calculation program, the dynamic display of the simulation results.For the Al-4.5%Cu alloy solidification, experiment research, analysis of metallograph and the same scale image contrast of alloy solidification sample. The results show that, the dendrite morphology and solute distribution and simulation results, which verifies the correctness of various models in the paper.Author Consider the nonlinear nature of material thermal physical parameters and high temperature mechanical performance parameters in7050aluminum alloy in the process of quenching, stress frame sample is object for study, there are simulated that temperature and thermal stressfield in7050aluminum alloy specimen in the process of quenching cooling with the nonlinear finite element software ABAQUS, The results indicate that numerical simulation of temperature field well reflects temperature field distribution of the specimen quenching, deformation features of stress frame sample and the recognition results are in line with the good.