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 effects of rare earth element La on microstructure and fracture toughness of Al-Li-Cu-Mg-Zr alloy were investigated by SEM and fracture toughness measurement. The experimental results show that the presence of Fe, Si, Na and other elements in the Al-Li alloy grain boundary segregation, adding a small amount of La can reduce the segregation of these impurities in the grain boundary. At the same time, the addition of La suppresses the growth of δ ’phase, reduces the precipitation of S’ phase, slows the aging process, and reduces the grain boundary free precipitation band width. Therefore, adding a small amount of La improves the fracture toughness of the Al-Li alloy.