Effect of strontium on the microstructure, mechanical, and tribological properties of the Zn-40Al-2Cu alloy

Abstract

Zn-40Al-2Cu and Zn-40Al-2Cu-0.1Sr alloys were produced by permanent mold casting method. The microstructure, mechanical properties and wear resistance of the produced alloys were investigated. Microstructural examinations were carried out using scanning electron microscopy and X-ray diffraction techniques. Hardness and mechanical properties of the alloys were determined through Brinell hardness measurement method and tensile tests, respectively. Tribological properties of the experimental alloys were investigated by using a ball-on-disc based wear test setup. It was observed that Zn-40Al-2Cu alloy consisted of alpha dendrites and the eutectoid alpha+eta phase mixture and copper-rich epsilon (CuZn4) phases located in interdendritic regions. Zn-40Al-2Cu-0.1Sr alloy contained mu (Zn-Sr-Cu-Al) phases in addition to alpha,alpha+eta, and epsilon phases. It was also observed that the dendrite size in the microstructure of the Zn-40Al-2Cu-0.1Sr alloy was smaller than that of Zn-40Al-2Cu alloy. Zn-40Al-2Cu-0.1Sr alloy exhibited higher hardness, tensile strength, and elongation to fracture values than Zn-40Al-2Cu alloy. Addition of strontium reduced the friction coefficient and wear volume value of Zn-40Al-2Cu alloy. The improvements in the friction coefficient and wear volume values of Zn-40Al-2Cu alloy with the addition of strontium were discussed based on the changes in the structural and mechanical properties of the alloy.