Chemical interaction between mild steel and liquid Mg–Si alloys

The reactivity between solid mild steel and liquid magnesium–silicon alloys has been experimentally investigated at 950–1000 K. At a Si content in the liquid of 0.025 at.%, an αFe(Si) transition zone slowly develops by balanced solid state diffusion of Si and Fe atoms. For Si contents in the liquid higher than 0.045 at.%, the transition zone is replaced by a layer of nearly stoichiometric α1Fe3Si. Growth of this layer proceeds at a fast rate, essentially by solid state volume diffusion of Fe atoms. For Mg–Si liquids containing 1–3.1 at.% Si, the thickness of the reaction zone, e, increases with the reaction time, t, according to a parabolic law e2=kt. The growth constant k, in m2 s−1, expresses as k=0.49 exp−(212 000/RT) with T in K and R=8.315 J K−1 mol−1.