Grains, Phases, and Interfaces an Interpretation of Microstructure
Grains, Phases, and Interfaces an Interpretation of Microstructure
复制标题
DOI：
--
复制
发表时间：
1948-06
期刊：
影响因子：
--
通讯作者：
C. S. Smith
中科院分区：
文献类型：
--
作者：
C. S. Smith
史密斯 1948 年发表的开创性论文《晶粒、相和界面——微观结构的解释》对科学家产生了长达 60 年的影响，并继续成为现代材料研究的基础。因为当前流行的是通过引用来衡量一篇论文对科学界的影响，所以我首先要指出的是，截至 2010 年 1 月，这篇论文自发表以来已被引用 831 次（根据 ISI 科学网）。这些引用的引人注目之处在于，其中100多次引用发生在2006年初至2009年底的4年间。这表明该论文在发表60年后仍然保持着与现代材料研究的相关性。我毫不怀疑材料科学专业的学生将来会继续阅读这部作品并从中受到启发。史密斯提出的基本思想是，微观结构的几何形状包含组成固体和液体的界面能的“印记”。因此，界面性质可用于预测材料加工过程中将形成的微观结构，相反，相对界面性质可根据微观结构的解释来确定。该分析基于错误取向晶体、不同固相、固体和液体或固体和气体之间的连接处界面能量的简单矢量平衡。在此框架内，假设通常在微观结构形成过程中的高温下获得局部平衡，则可以根据界面之间的二面角确定相对能量。整个分析过程通过 30 张精美的光学显微照片进行说明。史密斯在本文中提出的一个重要思想是晶界能量是各向异性的。虽然当时对晶界能量几乎一无所知，但史密斯主张基于二面角测量的各向异性。此外，通过观察孪晶界和随机晶界之间的连接，他意识到前者必须具有非常低的能量，而后者必须具有取决于边界面取向的能量。当然，这些结论已经被证明是准确的。还值得注意的是，虽然平面截面的显微照片是二维的，但真实的微观结构是三维的。过去，研究人员经常（也许很方便）忽视了这一点。然而，在整篇论文中，史密斯将显微照片中的二维信息与合理的三维排列联系起来。事实上，在这篇论文之后，史密斯首次利用颗粒分离技术和立体显微射线照相技术对三维颗粒形状进行了研究。这在今天似乎尤其重要，因为双束聚焦离子束扫描电子显微镜和高能 X 射线断层扫描等新工具首次使材料的三维内部微观结构可视化成为可能。
SMITH’S seminal 1948 paper, ‘‘Grains, Phases, and Interfaces—an Interpretation of Microstructure,’’ has influenced scientists for six decades and continues to be a base upon which modern materials research is built. Because the current fashion is to measure a paper’s impact on the scientific community through its citations, I’ll begin by noting that as of January 2010, this paper has been cited 831 times since it was published (according to the ISI web of science). What is remarkable about these citations is that more than 100 of them occurred in the 4-year period between the start of 2006 and the end of 2009. This demonstrates that the paper has maintained its relevance to modern materials research 60 years after it was published. I do not doubt that in the future students of materials science will continue to read, and be inspired, by this work. The basic idea put forth by Smith is that the geometry of a microstructure contains an ‘‘imprint’’ of the interfacial energies of the constituent solids and liquids. As a result, interfacial properties can be used to predict the microstructures that will be formed during materials processing and, conversely, relative interfacial properties can be determined from the interpretation of microstructures. The analysis is based upon the simple vector balance of interfacial energies at the junctions between misoriented crystals, different solid phases, solids and liquids, or solids and gasses. Within this framework, relative energies can be determined from the dihedral angles between interfaces, under the assumption of local equilibrium usually obtained at high temperature during microstructure genesis. The entire analysis is illustrated by 30 beautiful optical micrographs. One significant idea advanced by Smith in this paper is that grain boundary energies are anisotropic. While virtually nothing was known about grain boundary energies at the time, Smith argued for anisotropy on the basis dihedral angle measurements. Furthermore, from the observation that the junctions between twin boundaries and random grain boundaries, he realized that the former must have very low energies and that the latter must have an energy that depends on the boundary plane orientation. These conclusions, of course, have been proven to be accurate. It is also noteworthy that while micrographs from plane sections are two-dimensional, real microstructures are three-dimensional. In the past, researchers frequently (and perhaps conveniently) overlooked this point. However, throughout the paper, Smith relates the two-dimensional information in his micrographs to plausible three-dimensional arrangements. In fact, after this paper, Smith pursued the first studies of threedimensional grain shape using grain separation techniques and stereoscopic microradiography. This seems especially relevant today, as new tools such as the dual beam focused ion beam scanning electron microscope and high energy X-ray tomography make it possible for the first time to visualize the three-dimensional internal microstructures of materials.