• PDF / 785,321 Bytes
• 12 Pages / 593.972 x 792 pts Page_size
• 101 Downloads / 214 Views

DOWNLOAD

REPORT

---

INTRODUCTION

NANOCRYSTALLINE materials were first defined by Gleiter in 1981, who also presented ways to design them. Since then, the research about nanocrystalline materials and nanotechnology had been very active because of their unique physical and mechanical properties.[1–4] Certain experiments revealed that the measured properties of materials explicitly exhibited size dependence. For instance, the relationship of the strength and grain size followed the Hall–Petch relationship (rs = r0 + Kd1/2) for conventional polycrystalline materials, but it was not for the nanocrystalline materials, depending on nanostructure features.[1] The difficulties in experimental investigations are not only the huge cost but also the diversity of the measurements without physical models due to the different test conditions among so many individual researchers. With the advent of powerful modern material science, the multiscale simulation techniques in which either multiple time or multiple spatial scales are treated simultaneously may be the potential tool to deal with the complicated problem of microstructural evolution.[5,6] Y. WU, Ph.D. Student, and B.Y. ZONG, Professor, are with the Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004, People’s Republic of China. Contact e-mail: [email protected] X.G. ZHANG is Lecturer, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, and Department of Mathematics and Physics, Shenyang University of Chemical Technology, Shenyang 110142, People’s Republic of China. M.T. WANG, Engineer, is with Shanxi Taigang Stainless Steel Company Limited, Taiyuan 030003, People’s Republic of China. Manuscript submitted June 6, 2012. Article published online October 19, 2012 METALLURGICAL AND MATERIALS TRANSACTIONS A

Multiscale computational methodology is an integration of many different computational methodologies, and it is an intermediate tool to bridge from angstroms to microns. Some authors thought the idea of multiscale modeling bridged the analytical and numerical models;[7] others thought it should be extended to build up bridges between microstructural simulation and property predictions, and between processing modeling and property predictions.[8] Reference 9 describes the development of the quasi-continuum method linking atomistic and continuum models through the finite element method. Reference 10 presents a demonstration of the multiscale approach, which combined first-principles calculations, a mixed-space cluster expansion approach, and the diffuse-interface phase-field model. Many other kinds of computer simulation methods are developed vigorously, such as the first-principles (FP) calculation, molecular dynamics (MD) simulation, Monte Carlo (MC) method, and phase-field method. Generally, the FP calculation, MD simulation, and MC method are thought to be suitable for the analysis of nanostructure and properties, since these three models are all the typical simulation methods for