The diffusion characteristics of Mg-rare-earth diffusion couples were studi
ed. Cylinders of pure Mg and rare earth (Dy, Nd, and Pr) were abutted and a
nnealed at 500 degreesC for 100 h or 300 h. Point-by-point composition prof
iles were collected starting in pure Mg, across the diffusion zone, and end
ing in the pure rare earth, using energy dispersive x-ray spectroscopy with
a scanning electron microscope. The intermetallic phases that resulted due
to diffusion were identified and compared to existing phase diagrams, for
which the data is limited. For each diffusion couple, a plot of concentrati
on versus distance perpendicular to the original plane of contact was obtai
ned and analyzed using the Boltzman-Matano method. The interdiffusion coeff
icients for each set of phases were then calculated. The results show that
diffusion through the intermetallic phases is much slower than is expected
in a solid solution.