D. A. Samoshkin, R. N. Abdullaev, A. Sh. Agazhanov, S. V. Stankus
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引用次数: 0
摘要
本研究测量了锂含量为 21、25 和 30%的超轻镁锂合金在 185-775 K 温度范围内的等压热容,其中大部分测量是首次进行。测量采用差示扫描量热法,使用的是 DSC 404 F1 仪器。所得结果的不确定性估计为 2-3 pct。在此基础上开发的温度相关性和推荐数据表可用于科学和实际应用。对于所有研究的镁锂合金,在大约 220-260 K 的温度下,热容量会发生突然变化,这显然是由马氏体相变引起的。研究发现,在 250-685 K 的温度区间内,含 21-30% Li 的镁锂合金的比摩尔热容值实际上是相互吻合的,并且可以利用固体镁的热容温度依赖性在 DSC 测量不确定性的范围内进行估算。使用 Neumann-Kopp 规则可以估算所研究合金的热容量(精度不超过测量不确定度),但温度范围更窄,为 250-456 K。
Heat Capacity of Mg-Li Alloys with 21–30 at. pct Li in the Solid State
In the present study, the isobaric heat capacity of ultralight magnesium-lithium alloys with composition of 21, 25 and 30 at. pct Li were measured in the temperature range 185–775 K, most measurements were made for the first time. Measurements were performed by the method of differential scanning calorimetry using a DSC 404 F1 setup. The estimated uncertainty of the obtained results was 2–3 pct. The temperature dependences and the tables of recommended data on their basis were developed for scientific and practical application. For all studied Mg-Li alloys an abrupt change in the heat capacity was observed at the temperatures of about 220–260 K, which is apparently caused by the martensitic phase transformation. It was found that the specific molar heat capacity values of Mg-Li alloys containing 21–30 at. pct Li in the temperature interval of 250–685 K practically coincide with each other and can be estimated within the limits of DSC measurement uncertainties using the heat capacity temperature dependence of solid magnesium. It is possible to estimate the heat capacity of the studied alloys (with an accuracy not exceeding the measurement uncertainty) using the Neumann-Kopp rule, but in a much narrower temperature range of 250–456 K.