Characterization of texture in hexagonal materials using a line focus acoustic microscope

Abstract

In recent years considerable research has been devoted to the ultrasonic characterization ot the texture of rolled metal plates using the angular dependence of plate waves propagating in the plane of the plates. In this paper we have used a line focus acoustic microscope (LFAM) to measure the angular distribution of longitudinal surface skimming waves in Zr - 2.5% wt Nb samples exhibiting orthorhombic macroscopic symmetry. Using the information from longitudinal wave scans obtained on three principal planes, we attempt to determine as much information as possible about the five independent texture coefficients, W|mn, without any prior knowledge of the single-crystal elastic constants. In general, we find that only ratios of the texture coefficients and the isotropic longitudinal velocity component can be determined from the ultrasonic measurements, when performed on hexagonal materials with orthorhombic macroscopic symmetry. The results are averaging method independent and do not require any information about the density of the material.