MECHANO-STIMULATED EQUILIBRATION OF IRON MICROPARTICLES ON SAPPHIRE

Oleg Kovalenko Francois Oren Chikli Eugen Rabkin
Department of Material Science and Engineering, Technion-Israeli institute of Technology, Haifa

We applied a new method for equilibration of faceted submicrometer Fe particles on sapphire obtained by solid state agglomeration (dewetting) of metal thin film. The method relies on crystalline defects introduced in the particles by the atomic force microscopy-based indentation and tapping by hard diamond tip. The shape changes of individual crystals after plastic deformation followed by a heat treatment were investigated with the aid of Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), and compared with the changes of the pristine particles.

Over 400 deformed and pristine particles were examined. The shape of deformed particles evolved more readily than the shape of their pristine counterparts, approaching the equilibrium crystal shape. The Winterbottom analysis [1] was applied to 11 deformed particles exhibiting the highest aspect ratio. The resulting value of the work of adhesion (Wad) of the Fe(110)/Al2O3(0001) interface at 880 C ͦ was calculated assuming that these crystals have reached their equilibrium shape. The obtained value is Wad = 2.4 J/m2, which is nearly by a factor of two higher than the corresponding value for the molten Fe on sapphire [2].

[1] W.L. Winterbottom, Acta metall. 15 (1967) 303

[2] D. Chatain, I. Rivollet and N. Eustathopoulos, J. Chim. Phys., 83 (1986) 561









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