Microstructure and mechanical properties of the micrograined hypoeutectic Zn–Mg alloy

A biodegradable Zn alloy, Zn–1.6Mg, with the potential medical applications as a promising coating material for steel components was studied in this work. The alloy was prepared by three different procedures: gravity casting, hot extrusion, and a combination of rapid solidification and hot extrusion. The samples prepared were characterized by light microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analysis. Vickers hardness, tensile, and compressive tests were performed to determine the samples’ mechanical properties. Structural examination reveals that the average grain sizes of samples prepared by gravity casting, hot extrusion, and rapid solidification followed by hot extrusion are 35.0, 9.7, and 2.1 μm, respectively. The micrograined sample with the finest grain size exhibits the highest hardness (Hv = 122 MPa), compressive yield strength (382 MPa), tensile yield strength (332 MPa), ultimate tensile strength (370 MPa), and elongation (9%). This sample also demonstrates the lowest work hardening in tension and temporary softening in compression among the prepared samples. The mechanical behavior of the samples is discussed in relation to the structural characteristics, Hall–Petch relationship, and deformation mechanisms in fine-grained hexagonal-close-packed metals.