| A detailed examination has been carried out for clarifying the effects of rare-earth metals (La, Ce) addition on precipitation behaviors in Al-Li-Cu-Zr alloy. Present work was performed by means of the measurements of hardness, tensile strength and electrical resistivity, and the observation of transmission electron micrograph during ageing. The La and Ce elements added to 2090 alloy not only play leading role in retardation of peak age condition but in increasing strength and elongation of 2090 alloy. The δ′ and T₁, phases in the 2090 alloy containing La and Ce elements homogeneously distributed in the matrix and were finer than those of 2090 alloy at all ageing conditions. The δ′ phases, particularly, exist spherical shape in the specimen aged at 190℃ for 45hrs. Therefore, considering strength and elongation, the La, Ce may be estimated positive alloy addition element because of the improvement of strength, elongation in La, Ce addition alloy. |
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