Effect of Grain Refinement on Tensile Properties of Cast Zinc Alloys

The present work provides an insight into the relationships between grain size, solute content, and tensile properties of binary cast Zn alloys in order to understand the strengthening mechanisms in these alloy systems. Four groups of binary cast Zn-Mg and Zn-Al alloys with different grain sizes were designed. Two groups were produced to investigate the grain refinement strengthening and another two were for investigating the combined strengthening mechanisms of grain refinement and solid solution. Based on experimental results, the empirical relations between yield strength, grain size, solute content, and intrinsic friction were established. Then, the contributions of grain refinement and solid solution strengthening to the yield strength of cast Zn alloys were clarified and understood. Both solid solution strengthening and grain refinement strengthening were distinguished and quantified. The present results show that the variation of yield strength with grain size follows the Hall-Petch relation in both Zn-Mg and Zn-Al systems. Solid solution strengthening is proportional to c (0.52) (c represents the solute concentration in atomic percentage). The intrinsic friction of pure Zn was also determined to be around 11 MPa using an analytical method.