Influence of ECAP combined with ultrasound on the structure and properties of the alloy of the Mg-Zn-Zr system

The creation of implant systems based on bioresorbable metals and alloys within modern medical osteosynthesis techniques is one of the priority and actively developing areas of medical materials science. In this study, a new combined severe plastic deformation method was applied to the Mg-8.6Zn-1.2Zr alloy, which involves the simultaneous application of ultrasonic waves to the workpiece during equal-channel angular pressing. The effect of various deformation temperatures (400, 300, 200°C) and ultrasonic amplitudes (5 and 10 µm) on the structural characteristics and properties of the processed workpieces was investigated. It was found that at all considered deformation temperatures, the applied ultrasonic treatment leads to a reduction in the average grain size. Using the X-ray method, it was established that the application of ultrasound during ECAP leads to a significant increase in microstrains and dislocation density. The greatest increase in dislocation density occurs at an oscillation amplitude of 5 µm, with a maximum value of 10 ×1014 m−2 achieved at a temperature of 200°C. The highest strength was achieved at a temperature of 300°C and an oscillation amplitude of 10 µm, amounting to approximately 310 MPa. Moreover, for all considered states after ECAP with ultrasound, a high value of relative elongation exceeding 18% was characteristic. Under the same regime, the lowest corrosion rate of 4.5 mm/year was observed.