In order to determine a solution-treatment temperature for age hardening, specimens which had previously been slow cooled from 1 100°C were heated to temperatures ranging from 9300 to 1035'C in 15'C increments and quenched into an ice-water bath. Care was taken to break the quartz capsule containing the specimen immediately after quenching. The results indicated that heat treatments of 960'C or higher resulted in a single phase microstructure while at 945°C coarse precipitates were retai-ed. Thus a solution-treatment temperature of 1000°C followed by an icewater quench was used. The above solution-treatment resulted in a grain size of 210 pm. The following observations were made from TEM of solution-treated specimens. First, the absence of superlattice reflections that are characteristic of the ordered .xeta piiasc with a R? structure indicates that the Ti-23-11 alloy is disordered in the solution-treated condition. While an ordered B2 phase has been observed in other ' i-Nb-Al alloys (2-5), it should be noted that these contain more Nb and Al than the present alloy. Secondly, the omega phase was not observed. This is probably a result of the significant amount of Al (1 la/o) present; previous research has shown Al is effective in suppressing omega-phase formation (6). Thirdly, diffuse streaking is apparent in the P directions of the P zone axis selected area diffraction SAD pattern. Such streaking has been observed in other Ti-Nb-Al alloys (2-4) and has been attributed to a 1 1101 lattice instability in bcc-type lattices (7). Thus, we conclude that the Ti-23- 11 alloy retains a disordered bcc lattice upon quenching from 1000*C; athermal omega phase is not present.