MICROSTRUCTURES OF THE FeSiBNbCu SOFT MAGNETIC MATERIAL STUDIED BY HIGH RESOLUTION ELECTRON MICROSCOPY (HREM)

Vo Vong and Ng.Q.Thang

Laboratory of Electron Microscopy - National Centre for Natural Science and Technology, 18 Hoangquocviet Str., Caugiay Hanoi, Vietnam (vvemlab@ncst.ac.vn)

Microstructures of the magnetic material Fe_76,5-xCu₁Nb_xSi_13,5B₉ ,which was annealed at various temperatures between 500⁰C and 750⁰C in Ar-atmotphere and then melt-quenching, has been studied by high resolution electron microscopy.

Changes of the grain sizes, phases and nanocrystalline structure of the alloys under influences of the heat treatments have also been systematically investigated by the JEM-4000EX,which has accelerating voltage 400 kilovolt and resolution 0,17 nanomet .

In the work we present the method for preparation of brittle materials for TEM plan-view investigations.The wide areas , which electron beam can transmite , were received in the work.

The new results ,as well as, the alloys were changed from an amorphous state through a partially crystallized state at 550⁰ C and finally to a fully crystallized state at 750⁰C, will be submitted . Grains were observed when the sample was annealed at750⁰C, they have size from 60 to 82nm in diameter

The magnetic properties and microstructural evolution of the material have also been investigated.

References

1 Vong, V. (2000) The structural changes of the materials under influence of heat treatments, World Scientific Publishing, 670 - 673 Edited by Yeong-Der Yao

2 Hono, K., Hiraga, K., Wang, Q., Inoue, A. and Sakurai, T. (1992) The Microstructure Evolution of A Fe_73,5Si_13,5 B₉ Nb₃Cu₁ Nanocrystalline Soft Magnetic Material, Acta Metall. Mater. 40(9), 2137 – 2147 , 1992

Keywords : HREM, grain sizes , nanocrystaaline .