Exploring ω and α phase transformations in metastable β Ti-5553 alloy by in situ thermo-analytical techniques
摘要
This study employed thermo-analytical tools at different thermally treated samples to evaluate ω and α phase transformations in the Ti-5553 alloy. The ω dissolution and α precipitation were studied utilizing simultaneous thermal analysis (STA), X-ray diffraction (XRD), dilatometry, Vickers hardness measurement, optical microscopy, and scanning electron microscopy. Besides conventional XRD, in situ experiments were performed using a synchrotron light source. Considering the β-quenched condition as the initial state, five different phase transformations were detected, which include the ω precipitation and dissolution between 420 and 670 K (the low intensity of the ω dissolution thermal event required studying different aging treatments), and the α precipitation in three different mechanisms above 670 K. The aging at 573 K for 72 h allowed better detection of the ω dissolution event and was revealed to be an important experimental approach for phase transformations study. A contrast among in situ XRD, STA, and dilatometry techniques was verified in the thermal behavior of β-quenched and aged Ti-5553 alloy. The aging thermal treatments allowed the detection of ω phase dissolution by in situ XRD using a Cu Kα source, which was not achieved even using a synchrotron light source in the not-aged condition. These results exemplify the potential of experimental exploitation through thermo-analytical techniques and thermal treatments.