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采用原子分辨率成像和第一性原理计算,研究S析出相颗粒在高强Al-Cu-Mg合金晶粒内部的生长行为。结果表明,S相的形核和生长具有很强的各向异性特征和受温度影响的特征,同时伴随低维相转变。事实上,在较高的时效温度下(高于180°C),存在两种特征的GP区,它们决定S相晶体的生长机制。一种是S相本身的前驱体相,另一种是Guinier–Preston–Bagaryatsky(GPB)区的结构单元或其前驱体相。在较高温度下,GPB区的结构单元会在S相周围形成,并阻碍S相沿宽度方向的生长,导致S相长成柱状晶体;而在低温下,S相的生长不受GPB区的干扰,形成板条状形貌。
Atomic resolution imaging and first-principles calculations were performed to investigate the growth behavior of S precipitated phase grains in the grains of high strength Al-Cu-Mg alloy. The results show that the nucleation and growth of S phase have strong anisotropy and temperature-dependent characteristics, accompanied by low-dimensional phase transition. In fact, at higher aging temperatures (above 180 ° C), there are two characteristic GP zones that determine the growth mechanism of S phase crystals. One is the precursor phase of the S phase itself and the other is the structural unit of the Guinier-Preston-Bagaryatsky (GPB) region or its precursor phase. At higher temperatures, the structural units of the GPB zone are formed around the S phase and hinder the growth of the S phase in the width direction, resulting in S phase growing into columnar crystals; while at low temperatures, the S phase growth is not disturbed by the GPB zone , Forming a lath-like appearance.