日本金属学会誌

J. Japan Inst. Metals, Vol. 14, No. 3 (1950),
pp. 1-5

On the Superlattices of the Cu-Au System (I)

Makoto Hirabayashi, Seizo Nagasaki and Hideyo Maniwa


Abstract:

The Cu-Au system has a face-centered cubic lattice and possesses ordered structures for concentrations corresponding to Cu3Au and CuAu. Through the order-disorder transformation of these alloys, we have measured temperature dependencies of several physical properties : specific heat(Cp), temperature coefficient of electrical resistance (dρ/dθ) and thermal expansion coefficient(β).
The five specimens used have the following compositions : Au 23.4, 38.8, 44.5, 47.2 and 49.3 atomic% . The temperature dependencies of these three properties show the close parallelism for these five specimens. As for the alloys near CuAu (Au 94.3 and 47.2 at%), there are one kink and two peaks in Cp-temperature, dρ/dθ-temperature and β-temperature curves and there is a latent heat at the highest transition temperature (Fig. 1∼4). This behavior may be similar to that is already observed in the vicinty of MgCd.
Upon, reheating the quenched alloy (containing23.4 at%Au), the dρ/dθ-temperature curve shows an initial dip at about 200°C, the temperature where heat evolution began to be observed in the Cp-temperatrue curve(Fig. 6 and 7). It shows that even the formation of the small nuclei which gives rise to heat evolution at about 200° does affect the electrical resistance.
The results of these experiments are summarized in table 1.


(Received 1949/7/8)

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