Comparison of the microstructure, tensile, and creep behavior for Ti-24Al-17Nb-0.66Mo (atomic percent) and Ti-24Al-17Nb-2.3Mo (atomic percent) alloys

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2007-03, Vol.38 (3), p.529-536
• Main Authors: QUAST, J. P, BOEHLERT, C. J
• Format: Article
• Language: English
• Subjects: Alloys; Applied sciences; Creep; Creep (materials); Exact sciences and technology; Experiments; Grain boundaries; Grain size; Heat treating; Mechanical properties; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Molybdenum; Powder metallurgy; Scanning electron microscopy; Studies; Titanium alloys; Titanium base alloys
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-006-9074-5

The effect of small molybdenum additions, 0.66 and 2.3 at. pct, on the microstructure, tensile, and creep behavior of a nominally Ti-24Al-17Nb (at. pct) alloy was investigated. The alloy containing 2.3 at. pct Mo contained higher body-centered-cubic (bcc) phase volume fractions, which was expected as Mo stabilizes the bcc phase. Constant load, tensile-creep experiments were performed in the stress range of 29 to 275 MPa and the temperature range of 650 °C to 710 °C, in both air and vacuum environments. In-situ creep experiments were performed inside a scanning electron microscope chamber in order to identify the deformation evolution from surface observations. From these experiments, it was evident that α^sub 2^ intergranular cracking was prevalent and initiated the fracture process where the crack path followed the α^sub 2^ grain boundaries. The Ti-24Al-17Nb-2.3Mo (at. pct) alloy exhibited significantly lower creep rates than the Ti-24Al-17Nb-0.66Mo (at. pct) alloy, and this was associated with less contiguity of the α^sub 2^ phase. [PUBLICATION ABSTRACT]