Synergistic effect of Mg addition and hydrostatic extrusion on microstructure and texture of biodegradable low-alloyed zinc

The influence of synergic effect of different content of Mg and plastic deformation in the room temperature on microstructure and texture of low-alloyed zinc (ZnMg) was investigated in this work. Cast ZnMg alloys with three different Mg contents were hot extruded at 250 °C and subsequently subjected to hydrostatic extrusion (HE). Obtained alloys were compared to pure zinc. Detailed analysis of microstructure and local texture of ZnMg was performed on the longitudinal cross section of each sample, using scanning electron microscope equipped with electron backscatter diffraction. The macroscopic texture was investigated on the transverse cross section of each sample by means of the X-ray diffraction. Results showed that HE leads to grain refinement level unattainable with classic methods of deformation for both pure Zn and ZnMg alloys. Microstructural observation both with local and macroscopic texture analysis suggests the occurrence of dynamic recrystallization during plastic deformation. Addition of Mg caused major changes in microstructure of deformed materials and enhanced grain refinement. The bimodal structure consisted of grains elongated in the extrusion direction, as well as equiaxed ones was observed on the longitudinal cross section of ZnMg samples. Mg alloying combined with hydrostatic extrusion caused modification of the microstructure and texture in the zinc alloy samples which resulted in significant improvement of mechanical properties.