Ultrasonic Materials Characterization of Melt Spun Metallic Ribbons
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The rapid cooling rates obtainable by melt spinning techniques have enabled the production of nonequilibrium metallic glasses and microcrystalline alloys with enhanced solubility of solute elements. The recent and intensive development of rapidly solidified metal alloys has been accompanied by an extensive body of research concerning characterization of both material properties and preparation processes. Structural, magnetic, electrical and tensile properties have been investigated thus far. However, accurate characterization of elastic properties has been difficult because the final product achieved by melt spinning is usually a ribbon or foil with a thickness on the order of 50 μm or less. This geometry precludes the use of bulk ultrasonic waves for characterization of the elastic properties of these materials. Instead, guided waves must be utilized for the determination of elastic properties. Unlike bulk waves, the velocity of guided waves usually shows dispersion; velocity is a function of extrinsic factors, such as specimen thickness and ultrasound frequency. Hence, determination of elastic properties of ribbons from sound wave velocities cannot be achieved by direct substitution into appropriate equations.
KeywordsGroup Velocity Shear Wave Velocity Lamb Wave Defense Advance Research Project Agency Ribbon Thickness
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