ELASTIC PROPERTIES OF THE O-PHASE IN TI-AL-NB ALLOYS

Room-temperature elastic properties of the O phase in the Ti-Al-Nb sys tem have been studied using resonant ultrasound spectroscopy (RUS). Th e isotropic elastic constants of the O-phase in the polycrystalline te rnary alloys Ti-27Al-20Nb and Ti-27Al-25Nb were obtained. The results show that the room-temperature bulk, Young's, and shear moduli of thes e alloys are around 120, 130 and 50 GPa, respectively. The room temper ature Poisson's ratios are about 0.3. The Debye temperatures, theta(D) , were estimated to be approximately 410 K. The effect of alloying Ti- 27Al-20Nb with the transition metal elements Mo, Ta, Zr and V, and wit h silicon, on the elastic properties has been investigated. The variat ion of the Young's modulus with temperature has been determined for te rnary alloys and quaternary alloys using compression tests. (C) 1997 E lsevier Science Limited.