两种Ce微合金化铝锂合金形变热处理时的微观组织与拉伸性能

Microstructures and tensile properties on thermo-mechanical treatment for two kinds of Ce-microalloyed Al-Li alloys

研究了Ce添加量分别为0.09%及0.23%的Al-4.15Cu-1.25Li-X高强铝锂合金薄板T6态时效(175℃时效)及T8态时效(5%冷轧预变形+155℃时效)时的微观组织和拉伸性能。结果表明,相比T6态时效,T8态时效时铝锂合金强度及伸长率均有所提高。T8态时效时,含0.23%Ce的铝锂合金强度及伸长率均低于Ce含量为0.09%的铝锂合金。Ce含量增加未改变铝锂合金中时效析出相的种类,主要强化相仍为T1相(Al_2CuLi)及θ'相(Al_2Cu),但其数量减少。微量Ce的添加可形成含Ce且富Cu的Al_8Cu_4Ce相粒子,这些粒子在均匀化及固溶处理时均难以完全溶解。Ce含量增加,导致固溶基体中Cu含量降低,时效时含Cu析出相T1相及θ'相含量减少,铝锂合金强度降低。

The microstructures and tensile properties of high-strength Al-Li alloy Al-4. 15Cu-1. 25Li-X sheet containing 0. 09% and0. 23% Ce in the states of with T6 aging（ aging at 175 ℃） and T8 aging（ 5% cold rolling pre-deformation and aging at 155 ℃） were investigated. The result shows that comparing with T6 aging,both the strength and the elongation of Al-Li alloy with T8 aging are enhanced.Meanwhile,the strength and elongation of the T8-aged alloy containing 0. 23% Ce are lower than those of the alloy containing 0. 09% Ce.However,Ce concentration increased does not change the precipitate type,and the aging precipitates are still T1（Al_2CuLi） andθ＇（ Al_2Cu） phases,but their amounts are decreased. Thus,the addition of Ce causes the formation of Ce-contained and Cu-rich particles Al_8Cu_4Ce,which cannot be completely dissolved into the alloy matrix during homogenization and solution process. Finally,the concentration of dissolved Cu in solid solution is decreased with increasing of Ce concentration in the Al-Li alloy,which decreases the fraction of Cu-containing precipitates T1 and θ＇ after aging and weakens the alloy strength.