In对Al-3.5Cu合金析出过程的影响

利用透射电镜(TEM),差示扫描量热仪(DSC)等方法对Al-3.5Cu和Al-3.5Cu-0.5In(质量分数,%)合金中θ′相的生成及粗化行为进行对比研究。在175℃时效时In的添加显著地促进了合金的时效响应,时效峰值硬度提高了约200MPa。TEM观察结果显示富铟(In′)粒子在时效早期均匀析出,为θ′相的析出提供了非均匀形核位置;且在θ′相宽面发现了位于其片状顶角的In′粒子;时效后期含In合金中θ′相粗化速率明显小于无In合金。时效前增加6%预变形后两种合金时效响应及效果差别不大,证实T6状态In主要是通过淬火空位团簇,从而促进θ′相析出。

Effect of In Addition on Precipitation Process of Al-3.5Cu Alloy

The precipitation and coarsening behavior of θ’ phase in Al-3.5Cu and Al-3.5Cu-0.5In alloys(mass fraction,%) were investigated by transmission electron microscopy(TEM),differential scanning calorimetry(DSC) and some other methods.In addition markedly accelerates the aging response of Al-Cu alloy aged at 175℃,and raises the peak hardness by about 200 MPa.TEM observation shows that In-rich particles precipitate uniformly at the early stage of aging,which will act as heterogeneous nucleation positions of θ’ phase;In’ is observed at a corner of platelets having their broad face in the plane of view;θ’ phase is coarsened much more slowly in In-added alloy than in In-free alloy.With 6% pre-deformation before aging,these two alloys have similar aging response rate and strength,which confirms that in T6 state Indium facilitates θ’ precipitation mainly through quenched-in vacancies.