Microstructure and biodegradation behavior of as-cast and hot extruded Mg-5Zn-1Y alloy containing different amountsof calcium (0.0%, 0.1%, 0.5%, and 1.0%, mass fraction) were explored. The extrusion process was cond...Microstructure and biodegradation behavior of as-cast and hot extruded Mg-5Zn-1Y alloy containing different amountsof calcium (0.0%, 0.1%, 0.5%, and 1.0%, mass fraction) were explored. The extrusion process was conducted at three differenttemperatures of 300, 330, and 370 ℃. Chemical composition, phase constitution, microstructure, and biodegradation behavior of thealloys were investigated. The macro- and micro-scopic examination revealed that the addition of Ca refines the grain structure andforms an intermetallic phase, Ca2Mg6Zn3. The hot extrusion process resulted in breaking the intermetallic phases into fine particlesrouted to the extrusion direction. Moreover, dynamic recrystallization happened in almost all alloys, and more bimodalmicrostructure was formed in the alloys when the alloys were extruded at 370 ℃. Polarization curves showed no passive region,which indicated that active polarization dominated in the alloys; therefore, grain refining through Ca addition and dynamicrecrystallization over hot extrusion operation increased biodegradation rate. The results show that the as-cast Mg-5Zn-1Y-0.1Caalloy provides the highest corrosion resistance, and the extruded Mg-5Zn-1Y-0.5Ca alloy at 300 ℃ shows the lowestbiodegradation rate among the extruded alloys. Therefore, hot extrusion does not always improve the biodegradation behavior ofmagnesium alloys.展开更多
基金Shahid Rajaee Teacher Training University for the financial support (Vote No. 26234)
文摘Microstructure and biodegradation behavior of as-cast and hot extruded Mg-5Zn-1Y alloy containing different amountsof calcium (0.0%, 0.1%, 0.5%, and 1.0%, mass fraction) were explored. The extrusion process was conducted at three differenttemperatures of 300, 330, and 370 ℃. Chemical composition, phase constitution, microstructure, and biodegradation behavior of thealloys were investigated. The macro- and micro-scopic examination revealed that the addition of Ca refines the grain structure andforms an intermetallic phase, Ca2Mg6Zn3. The hot extrusion process resulted in breaking the intermetallic phases into fine particlesrouted to the extrusion direction. Moreover, dynamic recrystallization happened in almost all alloys, and more bimodalmicrostructure was formed in the alloys when the alloys were extruded at 370 ℃. Polarization curves showed no passive region,which indicated that active polarization dominated in the alloys; therefore, grain refining through Ca addition and dynamicrecrystallization over hot extrusion operation increased biodegradation rate. The results show that the as-cast Mg-5Zn-1Y-0.1Caalloy provides the highest corrosion resistance, and the extruded Mg-5Zn-1Y-0.5Ca alloy at 300 ℃ shows the lowestbiodegradation rate among the extruded alloys. Therefore, hot extrusion does not always improve the biodegradation behavior ofmagnesium alloys.