CORRELATION OF VARIOUS ELASTIC MODULI WITH RELATIVE DENSITY OF POROUS ALPHA-TWO TITANIUM ALUMINIDE COMPACTS
Theodore E. Matikas, Prasanna Karpur, Robert L. Crane, S. Shamasunder* USAF Wright Laboratory Materials Directorate (UDRI), WL/MLLP Wright-Patterson Air Force Base, OH 45433-7817 *USAF Wright Laboratory Materials Directorate (UES, Inc.), WL/MLLN Wright-Patterson Air Force Base, OH 45433-7817
The dynamic elastic moduli of the porous alpha-two titanium aluminide compacts are measured using a ultrasonic technique. Both shear and longitudinal velocities are measured for compacts of different densities, making computation of all the four elastic constants, viz., the Young's modulus, shear modulus, bulk modulus and Poisson's ratio. Ultrasonic techniques have been successfully used to measure the dynamic elastic moduli of porous compacts of a model material. By measuring the longitudinal and shear velocities as well as the density of a porous compact, it has been shown that the elastic moduli can be measured by properly accounting for the Poisson's ratio effect in the elastic half-space. It is seen that the elastic modulus, the shear modulus follow a power law relation as a function of relative density. With the choice of an appropriate form density function the relation can be presented with a linear model. The correlations of elastic and shear moduli with the relative density are found similar to the correlations of relative microhardness to density, indicating a possibility of mapping the elastic moduli, if the stress intensification factor of the material is known. The Poisson's ratio is seen to obey a linear correlation and the bulk modulus measured an exponential correlation with the relative density. The results obtained in this study are compared with some the earlier models. Some of the uncertainties in the earlier models are discussed and the possibility of using ultrasonic nondestructive methods for the measurement of density gradients as well as of anisotropy in the compacts is investigated.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 4, pages 2271 - 2274 Publisher:Ashgate Publishing Company
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