Выпуски

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2008

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том 6 / 

выпуск 1

 



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L. O. ANDRUSHCHIK, A. P. SHPAK, and S. P. OSHKADYOROV
«Physical Principles of Fine Crystalline and Nanostructured Materials Production by Sintering of Metal Powders Using Electrical Contact Heating»
153–215 (2008)

PACS numbers: 61.43.Gt, 61.46.-w, 81.05.Rm, 81.07.Bc, 81.07.Wx, 81.20.Ev, 81.40.-z

Theoretical results of the impact of defects on sintering process are described. The results on calculation of temperature difference in a contact region of par-ticles and in deep inside grain are presented. In the particles’ contact region, an electric resistance can grow due to changes in chemical composition (because of oxidation, segregation etc.) and to the complex structure of electric contact. As a result, when the electric current passes through the compressed powder ma-terial, the temperature increases in a contact region that results in a local for-mation of liquid phase at a final stage of high-rate electric heating. The theo-retical results on a possibility of the local formation of a liquid phase in the in-terparticle contact regions are experimentally confirmed for powder steels al-loyed with Cr, Mn, Mo and Ni. Fractographic and metallographic investiga-tions as well as measurements of the changes in mechanical properties are per-formed to support conclusion concerning the local melting. Analysis of changes in the structure and mechanical properties of sintered powder metallic materials fabricated by electrocontact heating shows that this method can be used for formation of nanostructure states in these materials and for develop-ment of nanotechnologies.

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