Temperature Dependence of Young's Modulus of Beta-Brass Single Crystals

Young's modulus of seven single crystals of beta-brass has been measured as a function of temperature from 25°C to 505°C for the purpose of studying the order-disorder phenomenon. The method used is that of the composite piezoelectric oscillator. The reciprocal of Young's modulus is linearly related to the orientation function at all temperatures. The maximum and minimum values of the reciprocal of Young's modulus, 1/${\mathrm{E}}_{\mathrm{}\left[100\right]\mathrm{}}$ and 1/${\mathrm{E}}_{\mathrm{}\left[111\right]\mathrm{}}$, are 3.881 and 0.475×${10}^{-12\mathrm{}}$ at room temperature and 4.970 and 0.583×${10}^{-12\mathrm{}}$ ${\mathrm{cm}}^2$/dyne at the critical temperature (468°C). The elastic anisotropy, given by ${\mathrm{E}}_{\mathrm{}\left[111\right]\mathrm{}}$/${\mathrm{E}}_{\mathrm{}\left[100\right]\mathrm{}}$, has the value, 8.2, at room temperature, decreases to a minimum, 7.2, at 300°C, and again increases to 8.6 at the critical temperature. Plots of the reciprocal of Young's modulus in three principal directions, [100], [110], and [111], show that the effect of disorder is mainly felt in the first two directions, while in the third direction the elasticity shows an approximately linear increase with increasing temperature. Before disorder sets in the elasticity in the [100] direction decreases with increasing temperature, contrary to the usual behavior of elastic materials.