An Overview of Accomplishments and Challenges in Recrystallization and Grain Growth
An Overview of Accomplishments and Challenges in Recrystallization and Grain Growth
复制标题
再结晶和晶粒生长方面的成就和挑战概述
DOI：
--
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
C. G. Roberts
中科院分区：
文献类型：
--
作者：
A. Rollett;A. Brahme;C. G. Roberts
多晶材料微观结构演化的研究已经活跃了几十年，因此阐明已取得的进展并指出一些仍然存在的挑战是很有趣的。晶界很重要，因为它们的长程运动在许多情况下控制着演化。我们对五个宏观自由度上晶界性质的基本特征有了一些了解。例如，过量自由能主要由构成边界的两个表面决定，尽管扭转分量也具有不可忽略的影响。尽管某些类别的材料（例如面心立方金属）有一些明显的趋势，但流动性的定义还不太明确。计算机模拟做出了重要贡献，例如，即使在不存在杂质的情况下，迁移率也表现出固有的晶体各向异性。在介观水平上，我们现在在三个维度上对单个晶粒的几何形状和生长速率之间有了严格的关系。我们正在根据 3D 无损测量来验证晶粒生长的计算机模型。包括织构发展在内的再结晶定量建模已在多个小组中完成。其他性能（例如耐腐蚀性）与微观结构定量相关。然而，仍然存在许多挑战。尽管经过了数十年的研究，我们仍然没有对大多数异常晶粒生长情况的完整因果描述。纳米结构材料对退火的响应可能导致意想不到的抗粗化，或者在意想不到的低温下粗化。尽管铝合金加工的具体情况已经取得了重大进展，但可应用于工业合金的再结晶的通用工艺模型仍然难以捉摸。薄膜经常表现出我们不完全了解的晶粒生长停滞以及异常晶粒生长。晶界以比我们理解的更复杂的方式对驱动力作出反应。显然，晶粒生长和再结晶方面仍然存在许多令人兴奋的挑战。
The study of microstructural evolution in polycrystalline materials has been active for many decades so it is interesting to illustrate the progress that has been made and to point out some remaining challenges. Grain boundaries are important because their long-range motion controls evolution in many cases. We have some understanding of the essential features of grain boundary properties over the five macroscopic degrees of freedom. Excess free energy, for example, is dominated by the two surfaces that comprise the boundary although the twist component also has a non-negligible influence. Mobility is less well defined although there are some clear trends for certain classes of materials such as fcc metals. Computer simulation has made a critical contribution by showing, for example, that mobility exhibits an intrinsic crystallographic anisotropy even in the absence of impurities. At the mesoscopic level, we now have rigorous relationships between geometry and growth rates for individual grains in three dimensions. We are in the process of validating computer models of grain growth against 3D non-destructive measurements. Quantitative modeling of recrystallization that includes texture development has been accomplished in several groups. Other properties such as corrosion resistance are being related quantitatively to microstructure. There remain, however, numerous challenges. Despite decades of study, we still do not have complete cause-and-effect descriptions of most cases of abnormal grain growth. The response of nanostructured materials to annealing can lead to either unexpected resistance to coarsening, or, coarsening at unexpectedly low temperatures. General process models for recrystallization that can be applied to industrial alloys remain elusive although significant progress has been made for the specific case of aluminum alloy processing. Thin films often exhibit stagnation of grain growth that we do not fully understand, as well as abnormal grain growth. Grain boundaries respond to driving forces in more complicated ways than we understood. Clearly many exciting challenges remain in grain growth and recrystallization.