金属间化合物
放热反应
高温计
熔点
合金
吉布斯自由能
材料科学
退火(玻璃)
铝
活化能
热力学
钛
相(物质)
烧结
化学工程
冶金
物理化学
化学
复合材料
温度测量
有机化学
物理
工程类
作者
Andrea Školáková,Pavel Salvetr,Jindřich Leitner,Tomáš Lovaši,Pavel Novák
出处
期刊:Molecules
[Multidisciplinary Digital Publishing Institute]
日期:2020-04-21
卷期号:25 (8): 1912-1912
被引量:16
标识
DOI:10.3390/molecules25081912
摘要
This work highlights new results on the synthesis of the TiAl3 intermetallic phase using self-propagating high-temperature synthesis. This method is considered a promising sintering route for intermetallic compounds. It was found that the reactions proceed in two stages. Below the melting point of aluminum, the Ti2Al5 phase forms at 450 °C after long annealing times by a direct solid-state reaction between the aluminum and titanium, and is converted consequently to TiAl3. This is a completely new finding; until now, many authors have believed in the preferential formation of the TiAl3 phase. The second stage, the self-propagating strongly exothermic reaction, proceeds above the melting point of aluminum. It leads to the formation of the TiAl3 phase accompanied by Ti2Al5 and Ti3Al phases. The reaction mechanism was shown in the form of chemical equations, which were supported by calculating Gibbs energy. Reaction temperatures (Tonset, Tmaximum, and Toffset) were determined after induction heating thanks to recording by an optical pyrometer. This finding provides completely new opportunities for the determination of activation energy at heating rates, in which common calorimeters are not able to detect a response or even measure. Now, the whole procedure will become accessible.
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