The undercooling of aluminum
The undercooling of aluminum
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DOI：
10.1007/bf02668565
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发表时间：
1987-06
期刊：
影响因子：
--
通讯作者：
B. Mueller;J. Perepezko
中科院分区：
文献类型：
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作者：
B. Mueller;J. Perepezko
凝固过程中影响组织发展的一个重要参数是形核前的过冷量。通过对液态金属粉末分散体的热分析测量，评估了铝的过冷潜力。已确定了许多影响粉末Al样品过冷度的变量，包括粉末涂层、粉末尺寸、熔体冷却速度和熔体过热度。俄歇电子能谱表面分析表明，改变粉末生产介质是改变涂层化学组成的有效方法。析因设计分析已被用于量化工艺变量提高铝可获得的过冷度水平的潜力。析因分析表明，通过改变粉末生产介质来控制粉末涂层对降低成核温度最为有效。此外，在低过热度(Ts=710°C)下高速冷却(T=500°C/S)时，在催化层最少的介质中生产的最细小的粉末获得了最深的过冷度，ΔT=175°C。这些研究为进一步增加过冷度和进一步研究在铝合金中产生稳定和亚稳定组织的凝固反应提供了基础。
An important parameter affecting microstructure development during solidification is the amount of undercooling prior to nucleation. The undercooling potential of aluminum has been assessed by thermal analysis measurements on powder dispersions of the liquid metal. A number of variables have been identified which influence the undercooling of powder Al samples including powder coating, powder size, melt cooling rate, and melt superheat. Surface analysis by Auger electron spectroscopy indicates that changing the medium in which the powders are produced is an effective method of altering the coating chemistry. Factorial design analysis has been employed to quantify the potential of processing variables to increase the undercooling level obtainable in aluminum. The factorial analysis indicates that control of the powder coating through changing the medium in which the powders are produced is most effective in decreasing the nucleation temperature. Additionally, the finest powders produced in the medium which induces the least catalytic coating, when cooled at high rates,T =500 °C/s, from low superheats,Ts= 710 °C, are found to achieve the deepest undercooling, ΔT = 175 °C. These studies provide the basis for further increases in undercooling and for future investigations into the solidification reactions which produce both stable and metastable structures in aluminum alloys.