Verification of Sandelin Phenomena in Mechanically Alloyed Fe–Zn and Fe–Zn–Si

Mechanical alloying through the ball-milling of elemental powders to form the zinc-rich ζ binary Fe–Zn alloy, and the ternaries consisting of 0.12 mass%Si, 1.2 mass%Si, and 2.4 mass%Si, based on the same Fe/Zn ratio was performed. These materials have been designated as ζ, ζ+0.12 mass%Si, ζ+1.2 mass%Si, and ζ+2.4 mass%Si and mechanically alloyed to form their metastable states, η-Zn, FeSi and ζ phases. Differential scanning calorimetry (DSC) measurements of the materials show the presence of characteristic exothermic and endothermic reactions during their continuous transformation to stable equilibrium states. In the ζ+0.12 mass%Si material composition (i.e., Sandelin region), we observe an invariant reaction peak at around 422°C, corresponding to both the eutectic reaction in the Zn–Si and the melting of Zn in the Fe–Zn systems. The observation of the FeSi phase for all the compositions, while absent in coatings of Si bearing steels suggests a relationship between the Sandelin effect and its formation.