Offerman S E, van Dijk N H, Sietsma J, Grigull S, Lauridsen E M, Margulies L, Poulsen H F, Rekveldt M Th, van der Zwaag S
Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft, Netherlands.
Science. 2002 Nov 1;298(5595):1003-5. doi: 10.1126/science.1076681.
The mechanical properties of polycrystalline materials are largely determined by the kinetics of the phase transformations during the production process. Progress in x-ray diffraction instrumentation at synchrotron sources has created an opportunity to study the transformation kinetics at the level of individual grains. Our measurements show that the activation energy for grain nucleation is at least two orders of magnitude smaller than that predicted by thermodynamic models. The observed growth curves of the newly formed grains confirm the parabolic growth model but also show three fundamentally different types of growth. Insight into the grain nucleation and growth mechanisms during phase transformations contributes to the development of materials with optimal mechanical properties.
多晶材料的力学性能在很大程度上取决于生产过程中相变的动力学。同步辐射源处X射线衍射仪器的进展为在单个晶粒水平上研究转变动力学创造了机会。我们的测量表明，晶粒成核的活化能比热力学模型预测的至少小两个数量级。新形成晶粒的观测生长曲线证实了抛物线生长模型，但也显示出三种根本不同的生长类型。深入了解相变过程中的晶粒成核和生长机制有助于开发具有最佳力学性能的材料。
