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The Comminution of Metal Powders.

Yardy, John W. (1967) The Comminution of Metal Powders. Doctoral thesis, University of Surrey (United Kingdom)..

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X-ray line broadening and transmission electron microscopy have been used to investigate the deformation structure of aluminium, copper, and nickel powders ball milled in an argon atmosphere. X-ray line broadening was analysed in terms of crystallite size and strain. Ball milling produced a decrease in crystallite size and an increase in the strain function. Electron microscopy indicated that the crystallite size corresponded to a cell or sub-grain structure within the powder particles. The substructure size decreased rapidly during ball milling until a limiting size was reached after which the rate of decrease was only slight. The limiting values were 200 A, 325 A, 475 A for copper, nickel and aluminium respectively. The limiting size effect was thought to be caused by dynamic recovery; the difference in size being explained by the effect of temperature and stacking fault energy. Annealing increased the crystallite size and was accompanied by a decrease in strain function. The changes in strain function may be considered to be associated with changes in dislocation arrangement in the cell walls and subboundaries. The strain function was seen to vary with crystallographic direction. Ball milling produced flake-like shaped particles which decreased in size with ball milling. The substructure size did not appear to be related to the particle size.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Yardy, John W.
Date : 1967
Contributors :
Additional Information : Thesis (M.Phil.)--University of Surrey (United Kingdom), 1967.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 15:16
Last Modified : 06 Nov 2018 16:54

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