*Article* **The Effect of Sn Addition on Zn-Al-Mg Alloy; Part I: Microstructure and Phase Composition**

**Peter Gogola \*, Zuzana Gabalcová, Martin Kusý and Henrich Suchánek**

Institute of Materials Science, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, Ulica Jána Bottu 25, 917 24 Trnava, Slovakia; zuzana.gabalcova@stuba.sk (Z.G.); martin.kusy@stuba.sk (M.K.); henrich.suchanek@stuba.sk (H.S.)

**\*** Correspondence: peter.gogola@stuba.sk

**Abstract:** In this study, the addition of Sn on the microstructure of Zn 1.6 wt.% Al 1.6 wt.% Mg alloy was studied. Currently, the addition of Sn into Zn-Al-Mg based systems has not been investigated in detail. Both as-cast and annealed states were investigated. Phase transformation temperatures and phase composition was investigated via DSC, SEM and XRD techniques. The main phases identified in the studied alloys were η(Zn) and α(Al) solid solutions as well as Mg2Zn11, MgZn2 and Mg2Sn intermetallic phases. Addition of Sn enabled the formation of Mg2Sn phase at the expense of MgxZny phases, while the overall volume content of intermetallic phases is decreasing. Annealing did not change the phase composition in a significant way, but higher Sn content allowed more effective spheroidization and agglomeration of individual phase particles.

**Keywords:** Zn-based alloy; phase composition; XRD; DSC; microstructure formation; Sn-addition; intermetallic phases
