S. Nag, R. Banerjee, University of North Texas, Denton, TX; P. Collins, H. Fraser, The Ohio State University, Columbus, OH; G. B. Viswanathan, Universal Energy Systems, Dayton, OH
Titanium alloys containing substantial amounts of b-stabilizing alloying additions often retain a single metastable b phase on fast cooling from above the b-transus temperature. However, strictly speaking this single b phase often consists of nanometer-scale solid-state decomposition products such as b phase separation, the omega and alpha phases. Ageing of these alloys after quenching results in coarsening of these phases, possibly accompanied with additional phase transformations. By employing 3D atom probe tomography, carried out in a local electrode atom probe (LEAP) instrument, these early stages of decomposition of the b phase have been investigated in some complex commercial alloys such as Ti-5Al-5Mo-5V-3Cr-1Fe (TIMETAL-5553 or Ti-5553) and Ti-35Nb-7Zr-5Ta (TNZT). While the former alloy is of interest in the aerospace industry, the latter alloy is of interest for biomedical applications. The results of these studies coupled with relevant TEM investigations of the same materials will be presented.
Summary: Titanium alloys containing substantial amounts of ƒÒ-stabilizing alloying additions often retain a single metastable ƒÒ phase on fast cooling from above the ƒÒ-transus temperature. However, strictly speaking this single ƒÒ phase often consists of nanometer-scale solid-state decomposition products such as ƒÒ phase separation, the omega and alpha phases. Ageing of these alloys after quenching results in coarsening of these phases, possibly accompanied with additional phase transformations. By employing 3D atom probe tomography, carried out in a local electrode atom probe (LEAP) instrument, these early stages of decomposition of the ƒÒ phase have been investigated in some complex commercial alloys such as Ti-5Al-5Mo-5V-3Cr-1Fe (TIMETAL-5553 or Ti-5553) and Ti-35Nb-7Zr-5Ta (TNZT). While the former alloy is of interest in the aerospace industry, the latter alloy is of interest for biomedical applications. The results of these studies coupled with relevant TEM investigations of the same materials will be presented.
