Development of the bifurcation theory for the microstructure changes and an application to the superalloys

微观结构变化分叉理论的发展及其在高温合金中的应用

基本信息

批准号：
09450235
负责人：
MIYAZAKI Toru
金额：
$ 6.78万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

Several interesting phenomena during microstructure evolution with aging have recently been observed when precipitate particles are elastically constrained. The typical exmples of the extraordinally behavior of the microstructure changes are 1) the deceleration of particle into several small particle. These phenomena have theoretically supported by "Shape Bifurcation Theory", proposed by us. In the present research, we study these interesting phenomena to get more wide range of experimental data and also to give more accurate theoretical background.The results obtained are as follows ;(1) The deceleration of particle coarsening is observed in Ni-Al-Ti alloy. The average particle size experimentally obtained when the coarsening rate started to slow down shows quite good agreement with the calculated value based on the shape bifurcation theory.(2) In the coarsening of the GP zone in Al-Zn system, the deceleration of the growth rate is observed experimentally. This time dependent slow down of the growth rate is investigated by the computer simulation on the basis of the Cahn-Hilliard non-linear diffusion equation. The time evolution of the wave length in mottled microstructure containing GP zones is calculated quantitatively. The shape bifurcation theory combined with the kinetic analysis by means of the computer simulation will extremely be a useful method to investigate the static and dynamic stability of the complex microstructure changes.(3) The morphological microstructure changes across the order/disorder phase transition line in the Fe-Si binary alloy is experimentally studied by using the "composition gradient method". The fine B2 domain structure was observed at the vicinity of the A2/B2 transition composition.

当沉淀物颗粒受到弹性约束时，最近观察到随着老化而发生的微观结构演变过程中的一些有趣现象。微观结构变化的异常行为的典型例子是1）粒子减速成多个小粒子。这些现象都有我们提出的“形状分岔理论”的理论支持。在本研究中，我们研究这些有趣的现象，以获得更广泛的实验数据，并提供更准确的理论背景。获得的结果如下：（1）在Ni-Al-Ti中观察到颗粒粗化的减速合金。当粗化速率开始减慢时，实验得到的平均粒径与基于形状分岔理论的计算值表现出很好的一致性。(2)在Al-Zn系GP区的粗化过程中，生长减速率是通过实验观察到的。基于 Cahn-Hilliard 非线性扩散方程，通过计算机模拟研究了这种随时间变化的生长速率减慢。定量计算了包含 GP 区域的斑驳微结构中波长的时间演化。形状分岔理论与计算机模拟动力学分析相结合，将成为研究复杂微观结构变化的静态和动态稳定性的一种非常有用的方法。(3)跨越有序/无序相变线的形态微观结构变化。采用“成分梯度法”对Fe-Si二元合金进行了实验研究。在A2/B2过渡组合物附近观察到精细的B2域结构。