MICROSTRUCTURE OPTIMISATION OF CENTRIFUGALLY CAST IN-SITU TIAL-BASED MATRIX COMPOSITE REINFORCED WITH TI2ALC PARTICLES

1 KAMYSHNYKOVA Kateryna
Co-authors:
1 LAPIN Juraj
Institution:
1 Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Bratislava, Slovakia, EU, kateryna.kamyshnykova@savba.sk, juraj.lapin@savba.sk
Conference:
28th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 22nd - 24th 2019
Proceedings:
Proceedings 28th International Conference on Metallurgy and Materials
Pages:
1504-1510
ISBN:
978-80-87294-92-5
ISSN:
2694-9296
Published:
4th November 2019
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
28 views / 12 downloads
Abstract

Samples of in-situ TiAl-based matrix composite reinforced with Ti2AlC particles were prepared by the centrifugal casting of Ti-47Al-5Nb-1C-0.2B (at.%) alloy. The as-cast samples were subjected to hot isostatic pressing (HIP) at 1360 °C to remove casting porosity. The applied HIP conditions resulted in a significant coarsening of as-cast grain structure connected with deterioration of mechanical properties. Two multi-stage heat treatment routes were proposed to refine the coarse grain structure of the HIP-ed samples. The pre-treatment of the composite in single α phase field followed by air cooling (AC), oil quenching (OQ) or water quenching (WQ) leads to the formation of massive γM(TiAl). The consequent annealing in the γ(TiAl) phase field followed by a stabilisation annealing at 900 °C leads to the formation of homogeneous fine-grained γ type of microstructure in the OQ and WQ samples. The solution annealing of the OQ and WQ samples in the α phase field followed by slow cooling results in the formation of refined equiaxed grains with nearly lamellar α2(Ti3Al) + γ microstructure. The contribution of several mechanisms to the grain refinement is analysed and discussed.

Keywords: TiAl, composites, casting, heat treatments, microstructure
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