Effects of Al Substitution for Zn on the Non-equilibrium Solidification Behavior of Zn–3Mg Alloys

Zn-based alloys may find many applications because of their excellent corrosion resistance and biocompatibility. It is of fundamental and technical interest to investigate their solidification behavior in casting. In this work, solidification paths of Zn–3Mg–2Al alloys were investigated using in situ X-ray diffraction and thermodynamic calculations. Results showed that a stable and a metastable solidification path of the samples are not much different from those of binary Zn–3Mg alloys. In each path, the Laves compound MgZn2 is the primary phase, and its growth is followed by growth of a metastable MgZn2/Zn eutectic or by a stable Mg2Zn11/Zn eutectic. Such observations can be explained in terms of thermodynamic calculations of driving forces for nucleation of stable and metastable phases.