Grain Boundary Microstrucural Control in Nanocrystalline Nickel by Magnetic Annealing

Tadao Watanabe 1Tsurekawa Sadahiro 1Palumbo Gino 2

1. Graduate School of Engineering Tohoku University,Department of Nanomechanics, Sendai 980-8579, Japan
2. Integran Technology Inc., Toronto, Canada

Abstract

How to improve the thermal and microstructural stability in nanocrystalline materials is a key subject for development of high performance and more reliable nanocrystalline advanced materials. It is well known that abnormal grain growth can easily take place and produce the heterogeneity of grain boundary microstructure in nanocrystalline materials. Most recently, it has been found that the annealing in a magnetic field can restrict abnormal grain growth, resulting in the formation of homogeneous grain structure in nanocrystalline nickel samples whose initial grain size was about 30nm, produced by electrolytic deposition. The grain boundary microstructures in magnetically annealed nickel specimens were analyzed by the orientation imaging microscopy (OIM) with a FE-SEM-EBSP system. It has been found that the thermal and microstructural stability can be improved drastically by magnetic annealing. The DSC analyses were also made to reveal the origin of the improvement of thermal stability of the grain boundary microstructures in nanocrystalline nickel. The result of DSC analyses for annealed in a magnetic field suggests a change of the grain boundary energy during annealing in a magnetic field. A new approach to the grain boundary engineering by the application of a magnetic field is demonstrated to be unique and promising to design and development of high performance and thermally stable advanced nanocrystalline materials.

 

Presentation: oral at E-MRS Fall Meeting 2003, Symposium G, by Tadao Watanabe
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-06-25 10:38
Revised:   2009-06-08 12:55