Measurement of texture in zirconium with a line-focus acoustic microscope

In recent years there has been considerable interest in the development of ultrasonic techniques for determining texture in cubic and hexagonal materials exhibiting orthorhombic macroscopic symmetry, However in essentially all of these studies, the accessible coefficients of the crystallographic orientation distribution function are determined from velocity measurements of waves propagating in the planes of thin plates or sheets. In the present paper the five coefficients W₂₀₀W₂₂₀. W₄₀₀, W₄₂₀. and W₄₄₀that are accessible from linear elastic measurements in hexagonal materials were determined from the angular dependence of the velocity of both Rayleigh and longitudinal waves measured in the three principal planes of zirconium samples that have orthorhombic symmetry. This technique involves less stringent requirements for absolute measurements of velocity. The velocities were obtained with an accuracy of ∼10-³ by analysis of V(z) curves produced with a line focus acoustic microscope operating at 225 MHz. The W_lmn coefficients were also determined by neutron diffraction and good agreement was found with the ultrasonic values.