Deviations from Matthiessen's rule in some magnesium-based alloys

Electrical resistivity measurements have been made on dilute and concentrated binary magnesium alloys containing Ag, Zn, Al, Nd, Pb, Sn and Th over the temperature range 77-320K. Small deviations occur from Matthiessen's rule for alloys that have been solution treated and quenched to retain the solid solution. Much larger deviations occur when the alloys are heat treated to precipitate the solute atoms from the solid solution. Possible causes of this effect are discussed.