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Formation and growth of iron, nickel and copper nuclei during gaseous reduction of their oxides
Author(s) -
Deo Brahma,
Chatterjee Sukanta,
Dube Ravindra Kumar
Publication year - 1988
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.198801553
Subject(s) - chemistry , metal , nickel , copper , crystallography , pyramid (geometry) , physics , optics , organic chemistry
Compacts of the oxides of the fcc metals gamma‐iron, nickel and copper were partially reduced at elevated temperatures in hydrogen and observed under scanning electron microscope to study the formation and growth pattern of metal nuclei during the very early stages of reduction. A characteristic but common feature of the nuclei growth pattern in the form of tetrahedral based pyramid was observed in all three metals. The habit plane for the growth of the metal nuclei is (111) while the growth planes are of (100) and (011) type. Although the initial shape of nuclei is of the form of a disc, it slowly transforms to tetrahedral based pyramid. This is explained in terms of mixed control mechanism of metal ion diffusion and oxygen removal from the surface. The sizes of nuclei are predicted and compared with the experimentally observed values.