A Study of Beta-Brass in Single Crystal Form

The resistances of twenty single crystals of brass in the beta-phase have been measured as a function of temperature from room temperature to about 550°C for the purpose of studying the order-disorder phenomenon. The results obtained are compared with the theory of Bragg and Williams. The resistivities at 25°C as a function of composition place the limits of the beta-phase at 51.3 and 55.5 atomic percent copper. A study of the thermal e.m.f. of the crystals against copper shows only a slight discontinuity in the second derivative of the e.m.f.-temperature curve at the temperature of complete disorder. The e.m.f. curves themselves are quite smooth. Young's modulus, $E$, for ten of the crystals, measured at room temperature, gives the elastic constant $S_{11}$, (44.8×${10}^{-13\mathrm{}}$ ${\mathrm{cm}}^2$/dyne) and the combination of constants, $2S_{12}+S_{14}$, (0.028×${10}^{-13\mathrm{}}$ ${\mathrm{cm}}^2$/dyne). A graph of $\frac{1}{E}$ against the orientation function, ($l^2{m}^2+m^2{n}^2+n^2{l}^2$) is linear. From it the ratio of the maximum to minimum $E$ is found to be 8.94. Below the elastic limit the stress-strain relation is linear with no permanent set nor hysteresis.