The constitution and age-hardening characteristics of certain duralumin-type alloys
File(s)
Author(s)
Ghate, Vithal Balwantrao
Type
Thesis
Abstract
The thesis is divided into three sections.
SECTION I.
Isothermal sections at 500°C. have been studied in the ternary system aluminium-copper-manganese and in the quaternary system aluminium-copper-magnesium manganese to enable a correlation to he made of the constitution with the ageing characteristics of certain Duralumin-type alloys.
The compositional ranges covered were approximately 0-6% copper, 0-5% magnesium and 0-2% manganese. In the quaternary isothermals, sections have been taken at constant manganese contents of 0.6, 1.2 and 1.8% and at constant copper contents of 3 and 4-5% respectively. No quaternary compound was detected. The quaternary isothermals have been discussed with reference to the perspective views of various phase regions.
SECTION II.
The effect of manganese additions up to 2% on the ageing characteristics of aluminium-copper alloys containing 3 and 4.5% copper was investigated by tensile measurements. It was found that (i) the shape of the ageing curves for 0.1% proof stress and tensile strength was similar to that of hardness/ageing curves, (ii) manganese additions of 0.5% or more refined the grain size and gave greater tensile strength and elongation in the fully-aged condition. The relationships between the properties and the constitution and the significance of grain size and modes of precipitation have been discussed.
SECTION III.
The effect of manganese additions on the age-hardening characteristics of the aluminium-copper-magnesium alloys has been studied by hardness measurements. It was found that (i) the manganese in the solid-solution increases the as-quenched and peak-hardness, (ii) the concentration of manganese beyond the solid solubility limit increases the as-quenched and peak-hardness but decreases the age hardening capacity due to the formation of the T-phase,
(iii) the T-phase has an accelerating effect on the ageing process
The various effects have been analysed with reference to the constitution and the precipitation process of the alloys.
An appendix has been added which summarises the results of an investigation of fractional nucleation in an aluminium - 4.25$ copper alloy.
Previous work relevant to all the three sections and the appendix has been reviewed.
SECTION I.
Isothermal sections at 500°C. have been studied in the ternary system aluminium-copper-manganese and in the quaternary system aluminium-copper-magnesium manganese to enable a correlation to he made of the constitution with the ageing characteristics of certain Duralumin-type alloys.
The compositional ranges covered were approximately 0-6% copper, 0-5% magnesium and 0-2% manganese. In the quaternary isothermals, sections have been taken at constant manganese contents of 0.6, 1.2 and 1.8% and at constant copper contents of 3 and 4-5% respectively. No quaternary compound was detected. The quaternary isothermals have been discussed with reference to the perspective views of various phase regions.
SECTION II.
The effect of manganese additions up to 2% on the ageing characteristics of aluminium-copper alloys containing 3 and 4.5% copper was investigated by tensile measurements. It was found that (i) the shape of the ageing curves for 0.1% proof stress and tensile strength was similar to that of hardness/ageing curves, (ii) manganese additions of 0.5% or more refined the grain size and gave greater tensile strength and elongation in the fully-aged condition. The relationships between the properties and the constitution and the significance of grain size and modes of precipitation have been discussed.
SECTION III.
The effect of manganese additions on the age-hardening characteristics of the aluminium-copper-magnesium alloys has been studied by hardness measurements. It was found that (i) the manganese in the solid-solution increases the as-quenched and peak-hardness, (ii) the concentration of manganese beyond the solid solubility limit increases the as-quenched and peak-hardness but decreases the age hardening capacity due to the formation of the T-phase,
(iii) the T-phase has an accelerating effect on the ageing process
The various effects have been analysed with reference to the constitution and the precipitation process of the alloys.
An appendix has been added which summarises the results of an investigation of fractional nucleation in an aluminium - 4.25$ copper alloy.
Previous work relevant to all the three sections and the appendix has been reviewed.
Version
Open Access
Date Issued
1958
Date Awarded
1958
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
West, Dr. D.R.E.
Eisher, Dr. M.S.
Sponsor
Government of Hyderabad; Government of Andhra Pradesh: Post-Graduate Scholarships.
Publisher Department
Department of Metallurgy - Royal School of Mines. Imperial College London.
Publisher Institution
University of London - Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)