利用微观Langevin方程对δ'相(Al3Li)沉淀过程的原子图像进行模拟研究,该方程不但能同时描述原子簇聚和有序化过程,将相分离和粗化在同一物理框架内考虑,而且无须预先设定第二相结构,可观察到动力学演化过程中可能出现的瞬时相.模拟结果表明:对于Al-15Li(原子分数,%)合金,最初在无序基体中出现的L12相浓度与无序相相同,在L12相之间形成重位点阵界面;随后,L12相有序度进一步增加,重位点阵界面逐渐转变为L12结构;最后形成被反相畴界分开的L12结构单相有序相.单相有序相一经形成.便开始分解,分解主要发生在反相畴界处,富Li区向平衡δ'相转化,贫Li区自发无序化,形成δ'相与无序基体共存的平衡结构.在沉淀过程后期.δ'相粗化特征明显,大颗粒长大,小颗粒变小或消失,两相界面由不规则变为平直.
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