Abstract γ′ phase (AlNi3) particles' precipitation behavior in the Cu–15Ni-xAl alloys (wt.%, x = 0, 1, 2, 3 and 4) ageing at different temperature was systematically discussed with the help of Calphad method. With fixed ageing temperature, when Al content increases from 1 wt% to 4 wt%, the γ′ phase particles transform from a few microns to dozens of nanometers in size. The increasing Al content was proven to raise the instability of single phase solid solution (FCC), which can be expressed by the increasing value of G e x c e s s F C C and will result in the increasing critical temperature for precipitation. Supersaturation at fixed ageing temperature is thus raised with increasing Al content, so does the nucleation driving force of γ′ phase. Simultaneously, the precipitation strengthening in Cu–15Ni–4Al firstly increases and then decrease with ageing temperature decreasing from 700 °C to 400 °C, which is due to the competition between increasing nucleation driving force and decreasing self-diffusion coefficient of element with decreasing temperature. The continuous and discontinuous precipitation behaviors of γ’ phase were also discussed, which will be respectively promoted and suppressed with decreasing ageing temperature due to the relatively high nucleation driving force. However, both continuous and discontinuous precipitation will be suppressed when the ageing temperature decreases to 400 °C due to the too low self-diffusion coefficient.

中文翻译：

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通过 Calphad 方法对 Cu-15Ni-xAl 合金中 γ' 相颗粒析出行为的新见解

摘要 借助Calphad 方法系统地讨论了Cu-15Ni-xAl 合金(wt.%, x = 0, 1, 2, 3 和4) 在不同温度下时效时γ'相(AlNi3) 颗粒的析出行为。在固定时效温度下，当Al含量从1wt%增加到4wt%时，γ'相粒子的尺寸从几微米转变为几十纳米。事实证明，Al 含量的增加会增加单相固溶体 (FCC) 的不稳定性，这可以通过 G 过量 FCC 值的增加来表示，并导致析出临界温度的增加。因此，随着Al含量的增加，固定时效温度下的过饱和度增加，γ'相的形核驱动力也随之增加。同时地，Cu-15Ni-4Al中的析出强化随着时效温度从700℃降低到400℃先增加后降低，这是由于随着温度降低，成核驱动力增加和元素自扩散系数降低之间的竞争。还讨论了γ'相的连续和不连续析出行为，由于较高的成核驱动力，随着时效温度的降低，分别促进和抑制γ'相的析出行为。然而，由于自扩散系数太低，当时效温度降低到400℃时，连续和不连续的析出都会受到抑制。这是由于随着温度的降低，成核驱动力的增加和元素自扩散系数的降低之间存在竞争。还讨论了γ'相的连续和不连续析出行为，由于较高的成核驱动力，随着时效温度的降低，分别促进和抑制γ'相的析出行为。然而，由于自扩散系数太低，当时效温度降低到400℃时，连续和不连续的析出都会受到抑制。这是由于随着温度的降低，增加成核驱动力和降低元素自扩散系数之间的竞争。还讨论了γ'相的连续和不连续析出行为，由于较高的成核驱动力，随着时效温度的降低，分别促进和抑制γ'相的析出行为。然而，由于自扩散系数太低，当时效温度降低到400℃时，连续和不连续的析出都会受到抑制。