(中南大學 材料科學與工程學院，長沙 410083)
摘 要: 通過顯微硬度測試和透射電鏡觀察，研究微量Sn和In對Al-3.5%Cu (質量分數)合金的時效特性及微觀組織演變的影響。結果表明：在Al-3.5%Cu合金中添加少量Sn能加速合金的時效進程并增強合金的時效硬化和強化效果，且復合添加0.15%In和0.15%Sn(質量分數)時合金的時效強化效果優(yōu)于添加0.3%Sn合金的；微量Sn、In的添加能明顯促進Al-3.5%Cu合金中θ′相的析出，并使之細小呈彌散分布；時效早期，Sn′ 粒子和Sn/In′ 粒子先于θ ′相析出，并可作為θ′相非均勻形核位置，從而增加了θ′相的形核率；微量Sn、In的添加能抑制θ′相的粗化，提高合金過時效性能。
關鍵字: 鋁合金；Sn；In；時效特性；微觀組織
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effects of trace Sn and In additions on the ageing behavior and microstructure evolution of Al-3.5%Cu alloy were investigated by the micro-hardness test and TEM. The results indicate that the trace addition of Sn can increase the ageing rate and enhance the effect of ageing hardening and strengthening. Compared with separate addition of 0.3%Sn (mass fraction) alloy, the addition of 0.15%In and 0.15%Sn has more favorable effect on the ageing strengthening. The trace addition of Sn and In to Al-3.5%Cu alloy can promote the precipitation of θ ′ phase, refine the precipitate and improve its distribution. During the initial stages of ageing, the Sn′ and Sn′(In′) particles precipitate earlier than θ ′ phase, which increases the nucleation rate of θ ′ phase by providing effective heterogeneous nucleation sites for θ′ phase. In addition, the additions of Sn and In can restrain the coarsening of θ ′ phase and enhance the age hardening response.
Key words: aluminum alloy; Sn; In; aging characteristics; microstructure
