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

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Abstract
The temperature variation of Young's modulus of beta‐brass single crystals of 55 atomic percent copper has been determined. Comparison is made with previously reported results. Internal friction has been measured at 21 and 42 kilocycles per second at room temperature and as a function of temperature to slightly above the complete disappearance of order. The room temperature decrement is for all crystals of the order of 10−4 and mainly independent of amplitude of oscillation. The decrement as a function of temperature shows a ``relaxation peak.'' Zener's theory for alpha‐brass is found to apply and the source of the relaxation is preferential orientation of pair axes of solute atoms in adjacent cells. The heat of activation is about 20×103 calories per mole. The relaxation peak is shown to be characteristic of the disordered state. There seems to be no relaxation phenomenon present in the ordered state. The effect of precipitation of the alpha‐phase on Young's modulus and the internal friction has been found negligible unless a large amount of precipitation occurs.