Acoustic study of texture in polycrystalline brass

Abstract

Resonant ultrasound spectroscopy was used to measure the orthorhombic elastic constants of rolled, polycrystalline plates of Cu, Cu–5% Zn, and Cu–15% Zn. The experimental results were fit to theoretical expressions to determine the orientation-distribution coefficients W400, W420, and W440. These coefficients are related to texture (the nonrandom orientation of crystallites). The experimental results were in good agreement with theory for the Cu and the Cu–15% Zn materials. The agreement was not as good for the more anisotropic Cu–5% Zn material, especially for the in-plane compressional constants C11 and C22. The ultrasonically derived W’s were compared to those obtained from neutron measurements for the Cu–Zn alloys. Pole plots based on the two types of measurements, using W400, W420, and W440, were in excellent agreement for the 15% Zn material, and in qualitative agreement for the 5% Zn material. The results support the idea that acoustic methods can be used to measure the low-order W’s in polycrystalline materials.