Pure Aluminum Single Crystal Study on Point Defect Dependence of Ultrasonic Longitudinal Wave Velocity

Abstract

In the authors' previous study, velocity changes of ultrasonic waves under simple and pure shear states were studied both theoretically and experimentally. The research work revealed the quite different longitudinal wave velocity changes between under the simple and pure shear states and also distinguished longitudinal velocity change under the pure shear state, on the other hand transverse wave velocity changes under simple and pure shear states showed almost the same change tendencies similar to the texture development under both shear states. Therefore, to clear the different effects due to plastic deformation on transverse and longitudinal waves velocity changes under simple and pure shear states the microstructural changes of polycrystal solids were investigated via finite element polycrystal model (FEPM). The analyzed results suggested that the transverse wave velocity depends upon texture developments mainly, whereas the longitudinal wave velocity depends heavily upon point defects induced by intersected cross slips among dislocations. The principal object of this paper is experimental verification of point defects dependence of the longitudinal wave velocity using a pure Aluminum single crystal. As a result, no point defects occurring under single slip stage was simulated by FEM analysis for crystal plasticity and experimental evidence of no longitudinal wave velocity changes under same stage was shown. It was confirmed that the longitudinal waves velocity depends under the point defects.