In-situ study on γ phase transformation behaviour of γ-TiAl alloys at different cooling rates |
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Institution: | 1. National Key Laboratory for Precision Hot Processing of Metals, School of Materials Science & Engineering, Harbin Institute of Technology, Harbin, 150001, China;2. Anhui Key Laboratory of High-performance Non-ferrous Metal Materials, Anhui Polytechnic University, Wuhu, 241000, China;3. Laboratory for Space Environment and Physical Sciences, Harbin Institute of Technology, Harbin, 150001, China |
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Abstract: | γ-TiAl-based alloys are promising lightweight high-temperature structural materials, and the transformation from the α parent phase to γ lamellae during the cooling process has a great influence on the microstructures and mechanical properties of TiAl alloys. In this paper, an in-situ observation technique, high-temperature laser scanning confocal microscopy (HTLSCM), was utilized to investigate the continuous cooling transition (CCT) from the α phase in three compositions. The nucleation and growth behaviors of γ lamellae were studied at several moderate cooling rates. In addition, the processes of helium gas quenching for three alloys were investigated, and the massive transformation was observed in Ti–49Al. CCT diagraphs were concluded for three alloys. The Vickers hardness of TiAl alloys subjected to different cooling rates was tested, and it was found that the hardness of alloys was enhanced with increasing cooling rate due to the refinement of lamellar spacing. |
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Keywords: | TiAl based Alloys High-temperature laser scanning confocal microscopy Nucleation and growth Phase transformation |
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