{beta}{prime} and {beta} precipitation in an Al-Mg alloy studied by DSC and TEM
- CNRS, Marseille (France). Centre de Thermodynamique et de Microcalorimetrie
Precipitation in Al-16 at. % Mg is investigated by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The shape of the {beta}{prime} formation DSC effect is interpreted with a novel theory and the curves obtained on the basis of this new theory fit well to the experimental curves. The s parameter derived from these fits, which is akin to the Avrami parameter n appearing in the Johnson-Mehl-Avrami-Kolmogorov model, is larger than 2.5, indicating that {beta}{prime} precipitation is an autocatalytic process. TEM showed the abundant presence of defects (mostly dislocation loops) but no evidence of nucleation of {beta}{prime} precipitates on these defects. The enthalpies of formation of the {beta} and {beta}{prime} phases are derived as 15.7 and 11.5 kJ per mol Mg, respectively.
- OSTI ID:
- 638306
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 10 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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