Characterization of the different precipitates
developed in supersaturated Al–1.12Mg2Si–0.35Si
(mass%) alloy by thermoelectric power (TEP) and electrical
resistivity (ER) measurements was considered. The
effect of precipitation of coherent, semi-coherent and noncoherent
phases on the TEP was found impressive in
describing different precipitates. Upon growing and
coherency loss of b0 particles, the TEP increases to reach a
maximum value. TEP begins to approach a stable value by
the formation of the equilibrium b (Mg2Si) precipitates and
then stabilizes with the complete growth of more stable
precipitates b phase and Si particles. The first-order coefficient
a of the ER–temperature dependence was found
dominating in the temperature range 300–635 K. Above
this temperature range, the second-order coefficient b starts
sharing effectively the resistivity–temperature dependence.
Furthermore, it has been shown that the range of temperature
in which the first-order coefficient a is dominating
slightly increases after slow cooling twice to the room
temperature in two successive runs. Correlation of a and b
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.