热压处理对气相合金化法制备的镁锌合金显微组织和耐蚀性的影响

Effect of Hot-Pressing Treatment on the Microstructure and Corrosion Resistance of Mg-Zn Alloy Prepared by Gas Phase Alloying Method

为了有效改善镁合金的性能,探究在冷凝和热压2种状态下,锌对镁合金的显微组织和腐蚀行为的影响,采用气相合金化法制备出Mg-Zn二元合金,并通过光学显微镜(OM)、X射线衍射仪(XRD)、电子扫描显微镜(SEM)、能谱分析仪(EDX)以及电化学工作站等手段进行研究和分析。结果表明:冷凝态和热压态的合金的物相均由α-Mg,MgZn,Mg_(7)Zn_(3)以及MgZn_(2)相组成。经300~360℃、压力为10 MPa条件下热压40 min后,合金的显微组织更均匀化、更致密,且逐渐形成条状组织;随着热压温度的升高,合金的腐蚀电流密度下降,耐蚀性增强。当热压温度为320℃,时间由4 h延长到12 h后,合金的塑性变形程度明显增大,析出细小的Mg_(7)Zn_(3)相增多,且分布均匀,合金的耐蚀性降低。

In order to effectively improve the properties of magnesium alloys,the effects of Zn on the microstructure and corrosion behavior of magnesium alloys under two states of condensation and hot-pressing were explored.The Mg-Zn binary alloy was prepared by gas phase alloying method,and the alloy was studied and analyzed by optical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDX)and electrochemical workstation.Results showed that the phases of alloy under two states of condensation and hot-pressing were composed ofα-Mg,MgZn,Mg_(7)Zn_(3) and MgZn_(2) phases.After hot-pressing treatment under the conditions of 300~360℃+10 MPa+40 min,the microstructure of the alloy became more uniform and denser,which also gradually formed strip structure.With increasing the hot-pressing temperature,the corrosion current density of the alloys decreased,and the corrosion resistance increased.When the time of the hot-pressing treatment extended from 4 h to 12 h at 320℃,the degree of the plastic deformation of alloy obviously enhanced,and the fine Mg_(7)Zn_(3) phases were precipitated and presented the uniform distribution.Besides,the corrosion resistance of the as-obtained alloy was weakened.