La对Al-Li合金时效组织和断裂韧性的影响

EFFECT OF MINOR La ON THE MICROSTRUCTRE AND FRACTURE TOUGHNESS OF Al-Li-Cu-Mg-Zr ALLOYS

通过电镜观察和断裂韧性测量,研究了稀土元素La对Al-Li-Cu-Mg-Zr合金微观组织和断裂韧性的影响。实验结果表明,在Al-Li合金中存在Fe,Si,Na等元素在晶界的偏聚,添加少量La可减少这些杂质在晶界的偏聚。同时,La的加入抑制δ′相的生长,减少S′相的析出,延缓时效过程,并且减少晶界无析出带宽度。因此,添加少量La提高了Al-Li合金的断裂韧性。

The effect of minor La on the microstructure and fracture toughness of Al-Li-Cu-Mg-Zr alloys was studied by electron microscope observation and the mea-surement of toughness. The results showed that some impurities, such as Fe, Siand Na, segregated to the grain boundaries in Al-Li alloys, the addition of minorLa to Al-Li alloys decreased the segregation of these impurities. La can delay thegrowth of δ' precipitates, decrease the density of S' precipitates and the widthof grain boundary precipitation free zones. Therefore, the toughness of Al-Lialloys containing minor La was improved.