A High‐Temperature Neutron Diffraction and First‐Principles Study of
Ti
3
AlC
2 and
Ti
3(
Al
0.8
Sn
0.2)
C
2
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| Authors: | Nina J Lane Sven C Vogel Sylvain Dubois Véronique Gauthier‐Brunet Guo Ping Bei Michel W Barsoum |
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| Affiliation: | 1. Department of Materials Science and Engineering, Drexel University, , Philadelphia, Pennsylvania, 19104;2. Los Alamos National Laboratory, Los Alamos Neutron Science Center, , Los Alamos, New Mexico, 87545;3. Département de Physique et Méchqnique des Matériaux, PPRIME Institute, UPR 3346, CNRS‐Université de Poitiers‐ENSMA, , F86962 Futuroscope Chasseneuil Cedex, France |
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| Abstract: | Herein, we report on the temperature‐dependent crystal structures of Ti 3 AlC 2 and Ti 3 Al 0.8 Sn 0.2 C 2 in the 373–1273 K temperature range, as determined by Rietveld analysis of high‐temperature neutron diffraction time‐of‐flight data. The compositions are 86(1) wt% Ti 3 AlC 2 and 14(1) wt% TiC 0.92(2) for the sample with no Sn , and 95(1) wt% Ti 3( Al 0.8 Sn 0.2) C 2 and 5(1) wt% Ti 2 AlC for the solid solution with Sn . The average linear volumetric thermal expansion is 8.0(2) × 10?6 K ?1 for Ti 3 AlC 2 and 8.2(5) × 10?6 K?1 for Ti 3( Al 0.8 Sn 0.2) C 2. The average linear thermal expansion in the a and c directions, respectively, are 7.6(2) × 10?6 K?1 and 8.9(2) × 10?6 K?1 for Ti 3 AlC 2. For Ti 3( Al 0.8 Sn 0.2) C 2, the respective values are 8.0(5) × 10?6 K?1 and 8.6(6) × 10?6 K?1. In the case of the solid solution, the quadratic thermal expansion coefficients are also given. Detailed bond lengths analysis shows that the thermal expansions along the a and c directions are controlled by the thermal expansions of the Ti – C , and Ti – Al bond lengths, respectively. The atomic displacement parameters (ADPs) show that the Al and Sn atoms vibrate with a higher amplitude than the Ti and C atoms. Consistent with first‐principles calculations, the ADPs of the Al/Sn site(s) in Ti 3( Al 0.8 Sn 0.2) C2 are lower than the ADPs of Al in Ti 3 AlC 2. |
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