Abstract
High-frequency acoustic measurements have been made of the elastic moduli and attenuation of single crystals of the Nb-H(D) system in the alpha - alpha ' phase. A novel transducer bonding method is described which allows accommodation of the volume change which accompanies alloying of Nb with H(D). This technique allows the acoustic measurements to be made throughout the alpha - alpha ' solid solution range up to H(D)/Nb=0.8 without interference from the phase transitions. The moduli and attenuation are determined as functions of temperature and frequency as the phase boundaries are approached, and the relaxations which precede the phase transitions are determined. The isotopic dependences of the moduli are determined throughout the alpha - alpha ' solid solution range.