少量Bi对2091 Al-Li合金拉伸性能和断裂行为的影响

THE INFLUENCE OF THE SMALL ADDITION OF BISMUTH ON THE TENSILE PROPERTIES AND FRACTURE BEHAVIOUR OF 2091 Al-Li ALLOY

本文研究了添加少量Bi对2091 Al-Li合金室温拉伸性能和断裂行为的影响,用俄歇电子能谱分析了杂质Na在晶界和晶内的分布情况。实验结果表明,在Na含量较高时,Na在晶界严重偏析,降低合金的强度和塑性。添加少量Bi能消除Na在晶界的偏析,强化晶界,减少低能沿晶断裂倾向,并能在一定程度上细化S′相和增加其析出密度,提高合金的强度和塑性。

The influence of the small addition of bismuth on the tensile properties and fracture behaviour of2091 Ai-Li alloy has been investigated. The distribution of impurity sodium on the grain boundaries andwithin the matrix was determined by Auger electron energy spectrum. The results showed that there wasthe severe grain boundary segregation of sodium in the Al-Li alloy with higher sodium content, which re-sulted in the decrease of the strength and ductility of Al-Li alloy. The small addition of bismuth can elimi-nate the grain boundary segregation of sodium, strengthen the grain boundaries and reduce the tendency oflow energy intergranular fracture. Bisides, a small addition of bismuth has the role of refining S' phaseand increasing the density of S' precipitates. Therefore, the Bi-containing 2091 Al-Li alloy provides ahigher combination of the strength and ductility.