微量Sn和In对Al-3.5%Cu合金时效行为及微观组织演变的影响

Effect of trace Sn(In) addition on ageing behaviour and microstructure evolution of Al-3.5%Cu alloy

通过显微硬度测试和透射电镜观察,研究微量Sn和In对Al-3.5%Cu(质量分数)合金的时效特性及微观组织演变的影响。结果表明:在Al-3.5%Cu合金中添加少量Sn能加速合金的时效进程并增强合金的时效硬化和强化效果,且复合添加0.15%In和0.15%Sn(质量分数)时合金的时效强化效果优于添加0.3%Sn合金的;微量Sn、In的添加能明显促进Al-3.5%Cu合金中θ′相的析出,并使之细小呈弥散分布;时效早期,Sn′粒子和Sn/In′粒子先于θ′相析出,并可作为θ′相非均匀形核位置,从而增加了θ′相的形核率;微量Sn、In的添加能抑制θ′相的粗化,提高合金过时效性能。

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.