In对Al-3.5Cu合金析出过程的影响

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

摘要:

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200 MPa。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。

Abstract:

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 oC, 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.