Journal of the Faculty of Engineering and Architecture of Gazi University 39:4 (2024) 2187-2196 Investigation of the effects of T5 and T6 heat treatments on the structural, mechanical, and tribological properties of Zn-40Al-2Cu-0.1Sr alloy Ali Paşa Hekimoğlu 1 * , Murat Hacıosmanoğlu 1 , Murat Tellioğlu 1 , Temel Savaşkan 2 1 Mechanical Engineering Department, Faculty of Engineering and Architecture, Recep Tayyip Erdogan University, 53100, Fener, Rize, Türkiye 2 Mechanical Engineering Department, Faculty of Engineering, Haliç University, 34060, Eyüpsultan, İstanbul, Türkiye Highlights: Graphical/Tabular Abstract  T5 heat treatment increases elongation to fracture of Zn-40Al-2Cu- 0.1Sr alloy.  T6 heat treatment increases hardness and tensile strength of Zn- 40Al-2Cu-0.1Sr alloy.  T5 and T6 heat treatment reduce wear volume of Zn-40Al-2Cu-0.1Sr alloy. Effects of T5 and T6 heat treatments on the structural, mechanical, and tribological properties of Zn-40Al- 2Cu-0.1Sr alloy produced by permanent mold casting method were investigated. The hardness, tensile strength, friction coefficient and wear volume values of the alloy in as-cast, T5 and T6 heat treated conditions are given in Figure A comparatively. Figure A. The bars showing the hardness, tensile strength, friction coefficient, and wear volume values of the Zn-40Al-2Cu-0,1Sr aloy in as-cast, T5 and T6 heat treated conditions Purpose: The purpose of this study is to investigate effects of T5 and T6 heat treatments on the structural, mechanical, and tribological properties of Zn-40Al-2Cu-0.1Sr alloy produced by permanent mold casting method. Theory and Methods: Zn-40Al-2Cu-0.1Sr alloy ingot was produced by permanent mold casting method. Microstructures of the produced alloys were examined with optical, scanning electron microscopy and XRD studies. The hardness of the alloy was determined by Brinell measurement method, and its mechanical properties were determined by tensile tests performed by a universal test machine. Dry sliding friction and wear tests were carried out according to ASTM: G99 using a ball-on-disc type tribotest machine. Results: As-cast microstructure of the alloy consisted of α dendrites, eutectoid transformation product of α+η phase mixture, copper-rich ε (CuZn4) particles, and μ(SrZnx) phase. T5 heat treatment had no significant effect on the dendritic microstructure of this alloy but T6 heat treatment removed it completely. T5 heat treatment decreased the hardness and tensile strength but caused a slight increase in the elongation to fracture of the alloy. T6 heat treatment caused an increase in hardness and tensile strength of the alloy but decreased its elongation to fracture. Both heat treatments (T5 and T6) increased the wear resistance of the alloy. Conclusion: T5 and T6 heat treatments can be applied for improving mechanical and tribological properties of Zn-40Al-2Cu-0.1Sr alloy. Especially, T6 heat treatment significantly increases the hardness, tensile strength, and wear resistance of the Zn-40Al-2Cu-0.1Sr alloy. Keywords:  Zn-40Al-2Cu-0.1Sr alloy  Microstructure  Mechanical properties  Friction  Wear Article Info: Research Article Received: 10.02.2023 Accepted: 26.11.2023 DOI: 10.17341/gazimmfd.1249792 Acknowledgement: This work was supported by Research Fund of the Recep Tayyip Erdogan University. Project Number: FYL-2021- 1245. Correspondence: Author: Ali Paşa Hekimoğlu e-mail: ali.hekimoglu@ erdogan.edu.tr Phone: +90 464 223 7518 / 1959