铝锂合金显微组织高分辨电子显微研究

Study on the microstructures of aluminum-lithium alloy by high resolution transmission electron microscopy

以新型高强铝锂合金(Al-Cu-Li)为研究对象,合金经过520℃固溶淬火后分别在165℃时效6 h和165℃时效18 h,然后采用高分辨电子显微镜观察Al-Cu-Li铝锂合金显微组织中δ′相和T1相的形貌和晶格像,研究了主要强化相T1相的形核机制。结果表明:单胞T1相为五层密排六方堆垛结构,T1相的化学堆垛次序为CBABC。观察发现T1相既可以单独在基体形核生长,也可以依附在原有的T1相上形核以台阶方式生长。细小的球形析出相δ′相为有序结构相,并且与基体共格。

The new high strength aluminum-lithium alloy（Al-Cu-Li） was taken as sample.After solid quenching at 520 ℃,the alloy was aged at 165 ℃ for 6 h and 18 h,respectively.Then,the morphology and lattice image of δ′ phase and T1 phase in microstructure of aluminum-lithium alloy were observed using high resolution electron microscope.The nucleation mechanism of main strengthening phase（T1 phase） was studied.The results indicated that the unit cell T1 phase had five-layer close-packed hexagonal stacking structure,and the chemical stacking sequence of T1 phase was CBABC.It was found that T1 phase not only could grow on matrix for nucleation,but also could grow on original T1 phase in the stepped form for nucleation.The tiny spherical precipitated phase（δ′ phase） was ordered structure phase,and was coherent with matrix.