摘要镍基高温合金以其优异的高温蠕变强度、抗疲劳性能、抗氧化和抗热腐蚀性能而被广泛应用于航空、航天领域。由于部件内外温差产生的温度梯度在高温部件中非常普通，温度梯度对微观组织和性能均产生很大影响，对该温度梯度在镍基合金中的影响进行研究，有助于理解合金的组织性能变化以及服役行为预测。33537
本文采用相场方法、周期性边界条件和半隐式傅里叶谱算法，在傅里叶空间中对Ginzburg-Landau方程和Cahn-Hilliard方程进行数值求解，利用Matlab7.0编程，研究了不同温度梯度下镍铝合金γ′相的沉淀过程的微观形貌演变，温度梯度对镍铝合金沉淀过程中γ′相体积分数、颗粒半径、颗粒数密度的影响规律。
通过对不同温度梯度下Ni-Al合金沉淀组织和动力学分析，发现随着温度梯度的增大，高温区γ′相的数量不断减少，块状的γ′相比例增大，粗化行为更加显著，颗粒半径增大，颗粒数密度减小，γ′相成分达到平衡值所需时间增加，γ′相的体积分数减小
关键词 温度梯度 镍基合金 相场 沉淀相
毕业论文设计说明书外文摘要
Title Study on the phase transformation behavior of Ni based alloy precipitation under temperature gradient
Abstract
Ni-based superalloys are the most widely used and have the highest strength at high temperature in superalloys.As Ni-Al alloys have good corrosion resistance, abrasion resistance and cavitation performance, showing excellent prospects.Temperature gradients are a common phenomenon in devices working at high temperatures,such as the superalloy blades in a turbine engine,the surface to the center of a nuclear fuel device and the solder joints of an electrical device.
Based on the Phase-field model,by using the periodic boundary conditions, Ginzburg-Landau and Cahn-Hilliard kinetic equation is solved with a semi-implicit fourier-spectral method.With Matlab7.0 programming,We investigated the microstructure evolution at different temperature gradients and the effects of temperature gradients on the the volume fraction ,particle radius and particle number density of γ′ phase in Ni-Al superalloys.
By analyzing the precipitation and dynamics of Ni-Al alloy under different temperature gradients, we find that with the increase of temperature gradient，γ′ phase of high temperature zone continuously reduces,the proportion of bulk γ′ phase increases,coarsening behavior is more significant,the radius of the particle increases and the density of the particles numbers decreases,the time which γ′ phase required to reach equilibrium value increases,the volume fraction of γ′ phase in Ni-Al superalloysdecreases,.
Keywords Temperature gradient Ni-base superalloys Phase field Precipitation
目 录
1 绪论 1
1.1 研究背景及意义 1
1.2 材料模拟研究方法 2
1.3 相场法组织模拟 3
1.3.2相场法模拟的步骤 4
1.3.3相场法发展现状 5
1.4合金沉淀转变理论 5
1.4.1经典理论 5
1.4.2非经典形核长大理论 7
1.4.3共格应变对粗化机制的影响 8
1.4.4沉淀过程的相场法模拟 8
1.5本文研究内容 8
2.相场模型 9
2.1相场模型的理论基础 9
2.2 模型法基本原理 11
2.3 镍铝合金相场模型的建立 12 温度梯度下镍基合金沉淀相的转变行为研究:http://www.751com.cn/cailiao/lunwen_30696.html