## 温度梯度下镍基合金沉淀相的转变行为研究

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. 源`自*六)维[论*文'网www.lwfree.cn
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

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.lwfree.cn/cailiao/20190302/30696.html
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