Al Cu Li and Al Mg Li alloys: Phase composition, texture, and anisotropy of mechanical properties (Review)
The results of studying the phase transformations, the texture formation, and the anisotropy of the mechanical properties in Al Cu Li and Al Mg Li alloys are generalized. A technique and equations are developed to calculate the amounts of the S1 (Al2MgLi) T1 (Al2CuLi) and d' (Al3Li) phases. The fraction of the d' phase in Al Cu Li alloys is shown to be significantly higher than in Al Mg Li alloys. Therefore, the role of the T1 phase in the hardening of Al Cu Li alloys is thought to be overestimated, especially in alloys with more than 1.5% Li. A new model is proposed to describe the hardening of Al Cu Li alloys upon aging, and the results obtained with this model agree well with the experimental data. A texture, which is analogous to that in aluminum alloys, is shown to form in sheets semiproducts made of Al Cu Li and Al Mg Li alloys. The more pronounced anisotropy of the properties of lithium containing aluminum alloys is caused by a significant fraction of the ordered coherent d' phase, the deformation mechanism in which differs radically from that in the solid solution.
Russian Metallurgy (Metally)