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Title: The behaviour of face centred cubic metals and alloys under simple reversed stresses
Author: Desvaux, Martin Patrick
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1967
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This thesis is an account of slip line investigations carried out at room temperature on single crystals of pure copper and a 12 at. pct. copper-aluminium alloy deformed under reversed stresses in tension and compression. Measurements on copper were made by the statistical determination, from surface replicas viewed in the electron microscope, of tensile and compressive slip line densities before and after a compressive strain which followed a tensile prestrain. Slip line densities were counted on a small region of the surface which had been re---electropolished after the tensile prestrain, and on an adjacent area which had not been re---electropolished. The difference found between compressive slip line densities in the two regions suggests that partial reverse slip takes place in copper. For copper-aluminium the electron microscope was used in conjunction with a new replica technique which enabled small changes in slip step height to be detected. New light is thrown on the mode of deformation of this alloy in tension, and under compression following a tensile prestrain, reverse slip is shown to occur. This reverse slip has been investigated in relation to the Bauschinger effect and it is caused by the dislocations generated during the tensile half cycle of deformation. Data concerning the Bauschinger effect is given for the alloy and the Bauschinger strain is found to be sensitive to the ageing time. Obstacles to dislocation movement which are set up in tension, break down in compression. The results are discussed in the light of current theories of cyclic strain hardening and the Bauschinger effect. A short review of the theories and experimental work which are relevant to cyclic strain hardening and to the Bauschinger effect are given.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available