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摘要
The effect of aging treatment on the microstructures and hardening behavior of a metastable beta Ti-9.2Mo-2Fe alloy, which is new designed on the basis of Bo-Md molecular orbital method (Bo, the bond order; Md, the metal d-orbital energy level), has been investigated using hardness measurement, X-ray diffraction, optical microscopy and TEM characterization. The results reveal that, the athermal omega phase with the size of 2-5 nm is found in Ti-9.2Mo-2Fe alloy when solution-treated at 860 degrees C followed by water quench. The isothermal x phase is also found when Ti-9.2Mo-2Fe alloy aged at temperatures from 300 degrees C to 500 degrees C, although the x phase has a limited time of stability at 400 degrees C and 500 degrees C. The athermal omega phase does not lead to attractive hardening due to its too small size and volume fraction, so the hardness of the solution-treated alloy is about 370 Hv. However, the isothermal x phase with the size of 5-10 nm shows a moderate hardening (470 Hv), while the x phase with the size of 50-100 nm contributes the best hardening (similar to 500 Hv). As well, the hardening due to isothermal x phase precipitation hardly exhibits over-aging response as long as x phase exists.
- 出版日期2013-2-5
- 单位北京有色金属研究总院
