Yttrium incorporation in Cr2AlC: On the metastable phase formation and decomposition of (Cr,Y)2AlC MAX phase thin films |
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| Authors: | Clio Azina Tim Bartsch Damian M Holzapfel Martin Dahlqvist Johanna Rosen Lukas Löfler Alba San Jose Mendez Marcus Hans Daniel Primetzhofer Jochen M Schneider |
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| Affiliation: | 1. Materials Chemistry, RWTH Aachen University, Aachen, Germany;2. Materials Design, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, Sweden;3. Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany;4. Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden |
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| Abstract: | Herein we report on the synthesis of a metastable (Cr,Y)2AlC MAX phase solid solution by co-sputtering from a composite Cr–Al–C and elemental Y target, at room temperature, followed by annealing. However, direct high-temperature synthesis resulted in multiphase films, as evidenced by X-ray diffraction analyses, room-temperature depositions, followed by annealing to 760°C led to the formation of phase pure (Cr,Y)2AlC by diffusion. Higher annealing temperatures caused a decomposition of the metastable phase into Cr2AlC, Y5Al3, and Cr-carbides. In contrast to pure Cr2AlC, the Y-containing phase crystallizes directly in the MAX phase structure instead of first forming a disordered solid solution. Furthermore, the crystallization temperature was shown to be Y-content dependent and was increased by ～200°C for 5 at.% Y compared to Cr2AlC. Calculations predicting the metastable phase formation of (Cr,Y)2AlC and its decomposition are in excellent agreement with the experimental findings. |
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| Keywords: | crystallization decomposition MAX phases metastable phase formation solid solution |
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