Quantification of the Mg{sub 2}Si {beta}{double_prime} and {beta}{prime} phases in AlMgSi alloys by transmission electron microscopy
- SINTEF, Trondheim (Norway). Applied Physics Dept.
A method has been developed to determine the density of the Mg{sub 2}Si {beta}{double_prime} and {beta}{prime} phases in 6xxx aluminum alloys using transmission electron microscopy (TEM). Age-hardened extruded profiles of an AlMgSi alloy, having different coarseness in the precipitate structure, were examined. By dark-field (DF) imaging, {beta}{double_prime} needles aligned in a (100) viewing direction were brought into contrast. Thickness was determined within 10% using a spot contamination method. After subsequent corrections, the number density of precipitates could then be quantified, usually with 5%. As expected, the average number density of the {beta}{double_prime} precipitates correlates well with the material`s tensile strength. A density of {beta}{prime} was obtained by a similar method. The densities represent maximum values since precipitate-free areas are not considered. Tensile strength is quite sensitive to the ratio between the number densities of {beta}{prime} and {beta}{double_prime}. By determining the volume of an average {beta}{double_prime} or {beta}{prime} needle, corresponding volume fractions of the phases can be determined. Quantification of these phases could benefit calculations involving mechanical properties of such alloys.
- OSTI ID:
- 109773
- Journal Information:
- Metallurgical Transactions, A, Vol. 26, Issue 8; Other Information: PBD: Aug 1995
- Country of Publication:
- United States
- Language:
- English
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