Yb对2519A铝合金抗剥落腐蚀性能的影响

Influence of Yb Addition on Resistance to Exfoliation Corrosion of Aluminum Alloy 2519A

采用铸锭冶金法制备了不同Yb含量的2519A铝合金试样,通过硬度测试、力学性能测试、金相显微镜、扫描电镜与透射电镜等分析方法研究了稀土Yb对2519A铝合金抗剥落腐蚀性能的影响。结果表明:在2519A铝合金中添加0.2%Yb(质量分数)时,Yb与Al,Cu,Fe和Mn形成稀土相,合金内粗大Al Cu相和Al Cu Fe Mn相数量减少,含Yb第二相粒子化学活泼性低于Al Cu相和Al Cu Fe Mn相。适量的Yb能细化合金的时效强化相,使其析出密度增加,阻止θ(Al2Cu)相在晶界上连续析出,减小晶界无沉淀析出带(PFZ)宽度,使晶界析出相变成非连续分布,从而改善了合金的剥落腐蚀抗力。当Yb含量进一步增加时,合金力学性能及抗剥蚀性能下降。

Influence of Yb additions on resistance to exfoliation corrosion of aluminum alloy2519 A was investigated in EXCO solution at ambient temperature, while the alloys were characterized by means of hardness test, tensile test, optical microscopy(OM), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results show that, with the addition of0.2%Yb, the amount of the coarse phases Al Cu phase and Al Cu Fe Mn decreased in the alloy due to the formation of phases of Yb compounds with Al, Cu, Fe and Mn, of which the chemical activity was inferior to that of the phases Al Cu and Al Cu Fe Mn. Meantime, the Yb addition could also refine the θ ′ phase and increase its area fraction, as a result, the continuous precipitation of θ(Al2Cu)phase at grain boundaries could be prevented, and the width of the precipitation free zone(PFZ)was shrunken at grain boundaries,therefore the resistance to exfoliation corrosion of the alloy could be improved. However an excessive addition of Yb might deteriorate the mechanical properties and the resistance to exfoliation corrosion of the alloys.