研究了时效处理对含Gd的AZ31镁合金显微组织和力学性能的影响,通过SEM,EDS对合金的显微结构进行了表征.结果 表明,AZ31镁合金中添加Gd后,优先形成了高熔点的A12Gd相,抑制了Mg17Al12相的生成;且随Gd含量的增加铸态合金的显微硬度呈现先增加后减小的趋势.对AZ31-xGd合金进行时效硬度分析,由时效硬化曲线确定了最佳T6处理工艺(500℃,16 h)+(200℃,32 h).在时效过程中,A12Gd相从颗粒状变为针状,再转变为短杆状最后团聚变成块状.铸态和时效态合金的力学性能随Gd含量的增加呈先增加后减小的趋势,这是由于时效析出的Al2Gd相具有弥散强化和析出强化的作用.

The corrosion behavior of AZ31 magnesium alloy with different Gd contents in 3.5%(mass fraction) Na2SO4 solution was investigated by mass loss method. The effect of rare earth Gd on microstructure,corrosion rate and corrosion morphology of AZ31 magnesium alloy was analyzed by optical microscope (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that adding rare earth Gd can improve the corrosion resistance of AZ31 magnesium alloy significantly. When the Gd content is less than 4.12%,the corrosion resistance of the alloy increases with the increase of Gd content, but when the Gd content is more than 4.12%,the corrosion resistance of the alloy declines at a certain degree with the increase of Gd content. This is mainly caused by the content of Gd, which exacerbates the micro-galvanic corrosion effect between the precipitation phase and matrix phase,and thereby results in the decline of the corrosion resistance of the alloy. So when the content of Gd is 4.12%,AZ31 magnesium alloy has the optimum corrosion resistance.