This study systematically investigated the microstructure,mechanical properties,and corrosion behavior of an extruded Zn-0.2Mg alloy processed by multi-directional forging(MDF)at 100℃.The mean grain size was remarkab...This study systematically investigated the microstructure,mechanical properties,and corrosion behavior of an extruded Zn-0.2Mg alloy processed by multi-directional forging(MDF)at 100℃.The mean grain size was remarkably decreased from 17.2±0.5µm to 1.9±0.3µm,and 84.4%of the microstructure was occupied by grains of below 1µm in size after applying three MDF passes.Electron backscattered difraction examinations revealed that continuous dynamic recrystallization,progressive lattice rotation,and particle-stimulated nucleation mechanisms were recognized as contributing to microstructural evolution.Furthermore,transmission electron microscopy results showed that nanoparticles of Mg/Zn dynamically formed under high strain MDF,while the initial extrusion fber texture was altered to be<0001>parallel to the fnal forging axis.A synergistic efect of grain refnement,texture evolution,second-phase precipitates,and dislocation strengthening resulted in an increased ultimate tensile strength of 232±5 MPa after three MDF passes.However,this was accompanied by a reduction in the elongation(8±2.1%).Additionally,a high corrosion rate of 0.59 mm/year was measured for the experimental alloy fabricated by 3 MDF passes.In agreement with the latter,electrochemical impedance spectroscopy results indicated that the grain refnement improved the passivation kinetics of the oxide layer.展开更多
In recent years,Zn-based materials have been extensively investigated as potential candidates for biodegradable implant applications.The introduction of alloying elements providing solid-solution strengthening and sec...In recent years,Zn-based materials have been extensively investigated as potential candidates for biodegradable implant applications.The introduction of alloying elements providing solid-solution strengthening and second phase strengthening seems crucial to provide a suitable platform for the thermo-mechanical strengthening of Zn alloys.In this study,a systematic investigation of the microstructure,crystallographic texture,phase composition,and mechanical properties of a Zn-3Ag-0.5Mg(wt%)alloy processed through combined hot extrusion(HE)and cold rolling(CR),followed by short-time heat treatment(CR+HT)at 200◦C was conducted.Besides,the influence of different annealing temperatures on the microstructure and mechanical properties was studied.An adequate combination of processing conditions during CR and HT successfully addressed brittleness obtained in the high-strength HE Zn-3Ag-0.5Mg alloy.By controlling the microstructure,the most promising results were obtained in the sample subjected to 50%CR reduction and 5-min annealing,which were:ultimate tensile strength of 432 MPa,yield strength of 385 MPa,total elongation to failure of 34%,and Vickers microhardness of 125 HV0.3.The obtained properties clearly exceed the mechanical benchmarks for biodegradable implant materials.Based on the conducted investigation,brittle multi-phase Zn alloys’mechanical performance can be substantially enhanced to provide sufficient plasticity by grain refinement through cold deformation process,followed by short-time annealing to restore proper strength.展开更多
文摘This study systematically investigated the microstructure,mechanical properties,and corrosion behavior of an extruded Zn-0.2Mg alloy processed by multi-directional forging(MDF)at 100℃.The mean grain size was remarkably decreased from 17.2±0.5µm to 1.9±0.3µm,and 84.4%of the microstructure was occupied by grains of below 1µm in size after applying three MDF passes.Electron backscattered difraction examinations revealed that continuous dynamic recrystallization,progressive lattice rotation,and particle-stimulated nucleation mechanisms were recognized as contributing to microstructural evolution.Furthermore,transmission electron microscopy results showed that nanoparticles of Mg/Zn dynamically formed under high strain MDF,while the initial extrusion fber texture was altered to be<0001>parallel to the fnal forging axis.A synergistic efect of grain refnement,texture evolution,second-phase precipitates,and dislocation strengthening resulted in an increased ultimate tensile strength of 232±5 MPa after three MDF passes.However,this was accompanied by a reduction in the elongation(8±2.1%).Additionally,a high corrosion rate of 0.59 mm/year was measured for the experimental alloy fabricated by 3 MDF passes.In agreement with the latter,electrochemical impedance spectroscopy results indicated that the grain refnement improved the passivation kinetics of the oxide layer.
基金This work was supported by the Polish National Science Centre[Grant number 2018/29/N/ST8/01703].
文摘In recent years,Zn-based materials have been extensively investigated as potential candidates for biodegradable implant applications.The introduction of alloying elements providing solid-solution strengthening and second phase strengthening seems crucial to provide a suitable platform for the thermo-mechanical strengthening of Zn alloys.In this study,a systematic investigation of the microstructure,crystallographic texture,phase composition,and mechanical properties of a Zn-3Ag-0.5Mg(wt%)alloy processed through combined hot extrusion(HE)and cold rolling(CR),followed by short-time heat treatment(CR+HT)at 200◦C was conducted.Besides,the influence of different annealing temperatures on the microstructure and mechanical properties was studied.An adequate combination of processing conditions during CR and HT successfully addressed brittleness obtained in the high-strength HE Zn-3Ag-0.5Mg alloy.By controlling the microstructure,the most promising results were obtained in the sample subjected to 50%CR reduction and 5-min annealing,which were:ultimate tensile strength of 432 MPa,yield strength of 385 MPa,total elongation to failure of 34%,and Vickers microhardness of 125 HV0.3.The obtained properties clearly exceed the mechanical benchmarks for biodegradable implant materials.Based on the conducted investigation,brittle multi-phase Zn alloys’mechanical performance can be substantially enhanced to provide sufficient plasticity by grain refinement through cold deformation process,followed by short-time annealing to restore proper strength.
