Development of prediction method of grain boundary and intragrain microstructures at an atomistic scale by utilizing GC Monte-Carlo methods.

利用GC蒙特卡罗方法开发原子尺度的晶界和晶内微观结构的预测方法。

基本信息

批准号：
16360314
负责人：
OKUDA Hiroshi
金额：
$ 7.62万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

Monte Carlo simulations have been applied to examine microstructural developments of precipitation structure at and near the grain boundary, to understand the formation mechanism of precipitation-free zone and influences of vacancy and solute atom depletions on the kinetics of PFZ formation. To realize simultaneous grain boundary and intragrain precipitations, we adopted Monte-Carlo simulation with the grain boundary set as a mass reservoir. This enabled us treating the whole system on a rigid lattice system.Vacancy depletion near the grain boundary simply delayed the whole precipitation kinteics, and no clear formation of PFZ was observed. In contrast, simultaneous grain boundary and intra grain precipitation lead to a formation of well-defined precipitation free zones, whose interface is defined by an abrupt extinction of precipitates, without any smooth change in the number density or size of precipitates. On the other hand, this simultaneous process poses a rather strict limitation between the PFZ width and interparticle distance, which should lie in the same order of magnitude. This does not necessarily agree with reported experimental observations. We found that a long-range solute depletion prior to precipitaion may lead to a PFZ microstructure whose PFZ width is far more larger than the interparticle distances of the precipitates, which agreed with actual PFZ microstructures in many cases.For the mutinary calculation required to examine the effects of vacancy-solute and solute-solute interaction, the code is still not efficient enough to simulate a model system large enough to examine the size including long-range depletion area for PFZ formation. This point needs further development.

已经应用了蒙特卡洛模拟，以检查晶界和附近降水结构的微结构发展，以了解无降水区的形成机理以及空位和溶质原子耗尽对PFZ形成动力学的影响。为了实现同时的晶界和内部沉淀，我们采用了蒙特卡洛模拟，将晶界集作为质量储层。这使我们能够在刚性晶格系统上处理整个系统。晶界附近的消耗只是延迟了整个降水狂热学，并且没有观察到PFZ的明显形成。相反，同时的晶界和晶粒内沉淀导致形成明确定义的无降水区，其界面是由沉淀的突然灭绝来定义的，而没有任何平滑的降水密度或沉淀物的大小的平滑变化。另一方面，这种同时的过程在PFZ宽度和粒子间距离之间构成了相当严格的限制，该距离应处于相同的数量级。这不一定与报道的实验观察结果一致。我们发现，在沉淀前的远距离溶质耗竭可能会导致PFZ微观结构，其PFZ宽度远比沉淀物的粒子间距离要大得多，该质量距离的跨粒子距离与许多情况下的实际PFZ微结构达成一致。在许多情况下，对于较大的模型而言，需要进行足够的模型，该模型的尺寸不足以进行较大的模型，并有效地进行了溶液 - 溶液 - 溶液 - 溶液 - 溶液 - 溶液 - 溶液 - 溶液 - 溶液 - 溶液 - 溶液 - 溶液 - - 溶液 - - 溶液互动的效果，均未进行模型的效果。 PFZ形成的远程耗竭区域。这一点需要进一步的发展。