Work supported by the Office of Energy Research, Office of Basic Energy Sciences, Materials Sciences Division of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098 (for studies on ceramics and γ-TiAl), the U.S. Air Force Office of Scientific Research under Grant No. F49620-96-1-0478 under the auspices of the Multidisciplinary University Research Initiative on High Cycle Fatigue ...

To modify the microstructure and enhance performances, the ultrasonic vibration is applied in the mould casting of TiAl alloy. The effects and mechanism of ultrasonic vibration on the solidifying microstructure and mechanical properties are investigated and the model for predicting lamellar colony size is established. After ultrasonic vibration, the coarse microstructure is well modified and la...

In contrast to practical hot compression processes, the testing of workability TiAl alloys is usually conducted under conditions constant strain rates and temperatures. This work aims at investigating microstructural evolution on a Gleeble-3800 thermomechanical simulator variable rate (0.1, 0.01 0.001 s−1) 1200 °C. The results show that, after holding time 30 s, abrupt change in ε = 0.3 (engine...

In order to identify the reasons for brittleness of a TNM-TiAl alloy (Ti51.05Al43.9Nb4Mo0.95B0.1 in at.%), plastic deformation behaviour ordered βo phase is investigated. The corresponding powder was densified by Spark Plasma Sintering produce near lamellar microstructure made γ/α2 colonies surrounded γ and grains. Then, room temperature tensile studied carrying out tests additional in-situ str...

Refining the grain size of γ-TiAl alloys to improve their strength and ductility is academic interest. Thus, we report a multi-stage heat treatment method consisting solution treatment, cyclic annealing, short aging refine microstructure Ti–48Al–2Cr–2Nb alloy. The solution-treated was refined from 1100 191 μm by promoting feathery γ packets. Fine duplex grains below 23 were obtained through dis...

It has been widely reported that the microstructure refinement of TiAl alloys can be achieved by massive transformation and subsequent annealing in α2 + γ two phase field. To achieve this goal, several heat treatment parameters must be adjusted, including the heat treatment temperature around single α phase field, the annealing temperature, and the annealing time for the precipitation of α2 pha...

This work reexamines the insertion of O atoms in L10 γ-TiAl system using first-principles calculations and thermodynamic modeling independent point defect approximation. It includes a study intrinsic defects, many alloying elements (more than twenty were considered), as well their interaction with oxygen. The formation complex defects composed either vacancies, anti-sites or solute is then stud...