Benisek Artur, Dachs Edgar, Salihović Miralem, Paunovic Aleksandar, Maier Maria E
Materialforschung und Physik, Universität Salzburg, Hellbrunnerstr. 34, A-5020 Salzburg, Austria.
J Chem Thermodyn. 2014 Apr;71(100):126-132. doi: 10.1016/j.jct.2013.11.012.
The heat capacities of two samples of a fcc Cu-Zn alloy with the composition CuZn15 and CuZn34 were measured from = 5 K to 573 K using relaxation and differential scanning calorimetry. Below ∼90 K, they are characterised by negative excess heat capacities deviating from ideal mixing by up to -0.20 and -0.44 J · mol · K for CuZn15 and CuZn34, respectively. The excess heat capacities produce excess vibrational entropies, which are less negative compared to the excess entropy available from the literature. Since the literature entropy data contain both, the configurational and the vibrational part of the entropy, the difference is attributed to the excess configurational entropy. The thermodynamics of different short-range ordered samples was also investigated. The extent of the short-range order had no influence on the heat capacity below = 300 K. Above = 300 K, where the ordering changed during the measurement, the heat capacity depended strongly on the thermal history of the samples. From these data, the heat and entropy of ordering was calculated. The results on the vibrational entropy of this study were also used to test a relationship for estimating the excess vibrational entropy of mixing.
采用弛豫法和差示扫描量热法，对两种成分分别为CuZn15和CuZn34的面心立方Cu-Zn合金样品，在5K至573K温度范围内测量了其热容。在约90K以下，它们的特征是具有负的过剩热容，对于CuZn15和CuZn34，分别偏离理想混合高达-0.20和-0.44J·mol·K。过剩热容产生过剩振动熵，与文献中可得的过剩熵相比，其负值更小。由于文献中的熵数据包含了熵的构型部分和振动部分，这种差异归因于过剩构型熵。还研究了不同短程有序样品的热力学。短程有序程度对300K以下的热容没有影响。在300K以上，测量过程中有序化发生变化，热容强烈依赖于样品的热历史。根据这些数据，计算了有序化的热和熵。本研究关于振动熵的结果也用于检验一个估算混合过剩振动熵的关系式。
