Reaction Diffusion in Mg–Cu System

Reaction diffusion in the Mg–Cu system has been investigated by an electron-probe microanalyzer. Two kinds of intermetallic compounds Mg2Cu and MgCu2 in the Mg–Cu diffusion couples were observed in the temperature range from 683 to 748 K. The Mg2Cu phase layer grows faster than MgCu2 phase layer. The growth rate of the Mg2Cu layer obeys a parabolic law as a function of annealing time and thus the growth turned out to be diffusion-controlled. The temperature dependence of the growth constant k of the Mg2Cu layer can be described with the Arrhenius equation:kMg2Cu=1.5×10−3exp[−(156±10)kJmol−1⁄RT]m2s−1.Kirkendall marker shift toward the Cu-rich side was found, which suggests that diffusion of Cu is faster than that of Mg.