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在单向凝固试验装置上研究了铝合金层状晶的生成条件,并对非小平面生长材料的孪生机理进行了分析。实验结果表明,层状晶的生成条件范围较宽,温度梯度、冷却速度和G/R~(1/2)比值是决定层状晶出现几率的主要参数。层状晶的形成是由晶体生长表面的原子堆垛层错引起的,溶质元素与铝的原子半径差和在铝中的偏析系数越大,越容易引起原子错排。层状晶枝晶主轴和与主轴成锐角的二次分枝均比柱状晶的生长速度快。层片增殖的机理与层状晶的起源相似,区别仅在于增殖的层片起源于层状晶枝晶二次分枝的端部。层状晶的形成既有一定的规律性,又有偶然性。
The formation conditions of the aluminum alloy layered crystals were studied on the unidirectional solidification device and the twin mechanism of the non-faceted growth material was analyzed. The experimental results show that the formation conditions of the layered crystals are wide, and the temperature gradient, the cooling rate and the G / R ~ (1/2) ratio are the main parameters that determine the probability of the layered crystals. The formation of lamellar crystals is caused by atomic stacking faults on the growth surface of the crystal. The difference in atomic radius between the solute elements and aluminum and the larger the segregation coefficient in aluminum lead to misalignment of atoms. Stratified dendrite main axis and the secondary axis at an acute angle than the columnar crystal growth rate faster. The mechanism of lamellar proliferation is similar to the origin of lamellar crystals except that the lamellar layer of proliferation originates at the ends of the secondary dendrites of lamellar dendrites. The formation of layered crystals both a certain regularity, but also by chance.