Correlative study of the thermoelectric power, electrical resistivity and different precipitates of Al-1.12Mg.sub.2Si-0.35Si alloy

• Published in: Journal of thermal analysis and calorimetry 2015-12, Vol.122 (3), p.1269
• Main Authors: Abo Zeid, E. F, Gaffar, M. A, Gaber, A, Mostafa, M. S
• Format: Article
• Language: English
• Subjects: Alloys; Electric properties; Specialty metals industry
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-015-4861-0

Characterization of the different precipitates developed in supersaturated Al-1.12Mg.sub.2Si-0.35Si (mass%) alloy by thermoelectric power (TEP) and electrical resistivity (ER) measurements was considered. The effect of precipitation of coherent, semi-coherent and non-coherent phases on the TEP was found impressive in describing different precipitates. Upon growing and coherency loss of β' particles, the TEP increases to reach a maximum value. TEP begins to approach a stable value by the formation of the equilibrium β (Mg.sub.2Si) precipitates and then stabilizes with the complete growth of more stable precipitates β phase and Si particles. The first-order coefficient α of the ER-temperature dependence was found dominating in the temperature range 300-635 K. Above this temperature range, the second-order coefficient β starts sharing effectively the resistivity-temperature dependence. Furthermore, it has been shown that the range of temperature in which the first-order coefficient α is dominating slightly increases after slow cooling twice to the room temperature in two successive runs. Correlation of α and β with the lattice rigidity of the alloy under investigation was established. Quenching and slow cooling affect strongly the observed correlation. All measurements in the present investigation were taken under non-isothermal conditions.