La对AZ80镁合金组织和性能的影响

利用光学显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)、电子万能拉伸试验机、AUT85729电化学工作站等设备研究了La对AZ80镁合金组织、力学性能和耐腐蚀性能的影响。结果表明,随着La的加入,铸态和挤压态AZ80合金的组织性能都得到了改善,晶粒尺寸减小,形成了新的杆状Al11La3相,但随着La含量的增加,杆状Al11La3的大小和数量逐渐增加,β-Mg17Al12相受到抑制,数量减少。La的添加提高了AZ80镁合金的强度和延展性,但当La含量增加到1%时,挤压AZ80合金的强度和延展性降低。采用电化学极化曲线测定了AZ80+xLa合金的耐腐蚀性,结果表明,La的加入提高了AZ80镁合金的耐蚀性。加入0.5%La后,AZ80镁合金力学和耐腐蚀综合性能达到最佳。

Effect of La on Microstructures and Properties of AZ80 Magnesium Alloys

In order to study the influence of La addition on the microstructures, mechanical properties and corrosion resistance of AZ80 magnesium alloys, experiments were carried out by means of optical microscopy, scanning electron microscopy, energy dispersive spectrometer, mechanical properties and electrochemical tests. The results showed that small amount of La addition changes the microstructure of as-cast and extruded AZ80 alloys, with the grain size being decreased and a new rod-shaped Al11La3 phase being formed;with the further increasing of La content, the size and amount of the rod-shaped Al11La3 phase gradually increased, and the precipitation of β-Mg17Al12 phase was suppressed. The strength and ductility were enhanced by adding La to AZ80 alloy. However, when the La content was added to 1%, the strength and ductility of the extruded AZ80 alloys were reduced. The corrosion resistance of AZ80+xLa alloys was evaluated by potentiodynamic polarization. The results showed that the corrosion resistance of AZ80 alloy was improved with the addition of La.Both mechanical properties and corrosion resistance reached an optimum with the addition of 0.5wt.% La.