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The Influence of Strain Rate on the Deformation of Aluminium Single Crystals.

Kovacs, Thomas. (1968) The Influence of Strain Rate on the Deformation of Aluminium Single Crystals. Doctoral thesis, University of Surrey (United Kingdom)..

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It is known that when metals are deformed at high strain rates they are usually more ductile. The object of this work was to find the crystallographic mechanism for this effect. The metal chosen was aluminium, because of the relative ease of producing single crystals. To grow very large single crystal strips a modified strain-annealing method was developed. The single crystal strips were later cut by electro erosion into suitable tensile specimens. An apparatus for producing rapid strain was built, based on compressed air and an explosive gas discharge into a confined volume containing a plunger connected to the tensile specimen. The specimens were pulled to fracture and were observed using high speed cine-photography. The fractured specimens were examined for elongation and their crystallographic rotations were recorded using X-ray diffractometry. Some selected specimens were subject to examination for slip line distribution using a scanning electron microscope. It was found that in some orientations the axial rotation of the crystals increased with increasing impact velocity while in other orientations it decreased. The orientation selected for investigation under the scanning electron-microscope showed decreasing slip line spacing with increasing deformation velocity. The measurements of overall elongation showed that there exists a critical velocity in single crystals. However, this critical velocity was found to be orientation dependent. The fracture mode appeared to be both orientation and velocity sensitive.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Kovacs, Thomas.
Date : 1968
Contributors :
Additional Information : Thesis (M.Phil.)--University of Surrey (United Kingdom), 1968.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 15:15
Last Modified : 06 Nov 2018 16:54

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