利用单晶研究了 Al?Cu 合金在弹性应力、屈服应力及塑性变形应力等加载条件下的应力时效行为，并分别通过透射电子显微镜(TEM)和压缩试验研究了应力时效后的显微组织与屈服强度。结果表明：15 MPa 的弹性应力就足够影响 Al?Cu 合金单晶在180°C 时效过程中θ′相的析出分布。沿着Al [116]方向加载的应力会增加 Al?Cu合金单晶(001)Al 惯析面上θ′相的析出密度。随着外加应力的增大，(001)Al 惯析面上θ′相的析出密度则会随之增加，进而导致 Al?Cu 合金单晶的屈服强度降低。通过应力产生的位错的影响及θ′相与 Al 基体之间的错配度作用的影响两个方面对应力时效时析出相择优分布的产生进行了讨论，结果更加符合θ′相与 Al 基体之间错配度作用的影响。
The stress aging behavior of Al?Cu alloy under various applied stresses, i.e., elastic stress, yield stress and plastic deformation stress, was investigated using single crystals. The resulting microstructures and the yield strength were examined by transmission electron microscopy (TEM) and compression tests, respectively. The results indicate that an elastic stress of 15 MPa is high enough to influence the precipitation distribution of θ′ during aging at 180 °C. The applied stress loading along Al [116] direction results in increased number density of θ′ on (001)Al habit planes. This result becomes more significant with increasing applied stress and leads to lower yield strength of Al?Cu single crystals during aging. Moreover, the generation of the preferential orientation of θ′ was discussed by the effect of the dislocation induced by applied stress as well as the role of the misfit between theθ′-precipitate and Al matrix. The results are in agreement with the effect of the latter one.
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