Structure and Properties of Directionally Solidified Mo-8.7 Si-18 B Alloys

Юрій Іванович Богомол, Ольга Ігорівна Попович, Маня Крюгер, Петро Іванович Лобода

Abstract


Background. The research of alloys of the Mo–Si–B-system, which are a new type of heat-resistant alloys for the manufacture of gas turbine blades to replace nickel single crystal superalloys.

Objective. The purpose is to study the effect of the kinetic parameters of crucibleless melting zone and redundancy of boron on the regularity of directionally solidified eutectic Mo-8.7 at. % Si-18 at. % B alloy’s formation of structure and mechanical properties.

Methods. Directionally solidified Mo-8.7 at. % Si-18 at. % B and Mo-8.7 at. % Si-18.5 at. % B alloys were produced by crucibleless melting zone of not sintered powder compacts. Microstructure analysis of the obtained reinforced composites and chips, X-ray analysis, the study of micromechanical properties with a dispersion analysis of the data were conducted.

Results. Directionally solidified Mo-8.7 % Si-18 % B, Mo-8.7 % Si-18.5 % B alloys and fast solidified Mo-8.7 % Si-18.5 % B alloy were produced, their microstructure consists of intermetallic matrix reinforced with inclusions of solid solution of molybdenum. Integrated micro hardness of the received alloys reaches 11.86 ± 1.49 GPa and fracture toughness – 6.92 ± 0.68 MPa×ml/2.

Conclusions. The increase of the rate of crystallization leads to a natural refinement of the structure and increase of the anisotropy in matrix phase. It is shown that the introduction of boron in amount of 0.5 at. % leads to a decrease of the equilibrium from Mo-Mo5SiB2-Mo3Si to Mo-Mo5SiB2-Mo2B. The microhardness is anisotropic and fracture toughness is mostly isotropic.

Keywords


High-temperature structural materials; Crucible-free zone melting; Directional solidification; Mo–Si–B-system; Microstructure; Phase composition; Microhardness; Fracture toughness

References


A. Lemberg and R.O. Ritchie, “Mo-Si-B alloys for ultrahigh-temperature structural applications”, Advanced Materials, vol. 24, no. 26, pp. 3445–3480, 2012. doi:10.1002/adma.201200764

F. Wang et al., “Microstructure and oxidation behavior of directionally solidified Mo–Mo5SiB2 (T2)–Mo3Si alloys”, J. Alloys Compounds, vol. 462, no. 1-2, pp. 436–441, 2008. doi:10.1016/j.jallcom.2007.08.064

T. Parthasarathy et al., “Oxidation mechanisms in Mo-reinforced Mo5SiB2(T2)–Mo3Si alloys”, Acta Materialia, vol. 50, no. 7, pp. 1857–1868, 2002. doi:10.1016/S1359-6454(02)00039-3M

N.S. Senyushkyn, “Methods to increase the efficiency of power units based on gas turbine engine”, Molodoi Uchenyi, vol. 1, no. 7, pp. 53–55, 2011 (in Russian).

J. J. Kruzic et al., “Ambient- to elevated-temperature fracture and fatigue properties of Mo-Si-B alloys: Role of micro­structure”, Metallurg. Mater. Trans. A, vol. 36, no. 9, pp. 2393–2402, 2005. doi:10.1007/s11661-005-0112-5

I.Y. Kryklyva et al., “Alloys of the Mo-Si-B- system”, Fizyka i Himiya Tverdoho Tila, vol. 12, no. 2, pp. 365–369, 2011 (in Ukrainian).

H. Nowotny et al., “Untersuchungen in den Dreistoffsystemen: Molybdän-Silizium-Bor, Wolfram-Silizium-Bor und in dem System: VSi2−TaSi2”, Monatshefte für Chemie, vol. 88, no. 2, pp. 180–192, 1957. doi:10.1007/BF00901624

M. Krüger et al., “Mechanically Alloyed Mo–Si–B alloys with a continuous α-Mo matrix and improved mechanical properties”, Intermetallics, vol. 16, no. 7, pp. 933–941, 2008. doi:10.1016/j.intermet.2008.04.015

J.H. Perepezko et al., “Phase stability in processing and microstructure control in high temperature Mo-Si-B alloys”, in MRS Proc., Warrendale, 2000, vol. 646, pp. 253–259. doi:10.1557/PROC-646-N4.5.1

P.I. Loboda, “Features of structure formation with zone melting of powder Boron-containing refractory materials”, Powder Metallurgy and Metal Ceramics, vol. 39, no. 9-10, pp. 480–486. doi:10.1023/A:1011322707881

D. Zhou et al., “Crystal structure and physical properties of Mo2B: First-principle calculations”, J. Appl. Phys., vol. 115, no. 11, p. 113504, 2014. doi:10.1063/1.4869055

R.L. Ashbrook, “Directionally Solidified Ceramic Eutectics”, J. Amer. Ceramic Soc., vol. 60, no. 9-10, pp. 428–435, 1977. doi:10.1111/j.1151-2916.1977.tb15527.x

J. Llorca and V.M. Orera, “Directionally solidified eutectic ceramic oxides”, Progress Mater. Sci., vol. 51, no. 6, pp. 711–809, 2006. doi:10.1016/j.pmatsci.2005.10.002


GOST Style Citations


  1. Lemberg J.A., Ritchie R.O. Mo-Si-B alloys for ultrahigh-temperature structural applications // Advanced Materials. – 2012. – 24, № 26. – P. 3445–3480. doi:10.1002/adma.201200764

  2. Microstructure and oxidation behavior of directionally solidified Mo–Mo5SiB2 (T2)–Mo3Si alloys / F. Wang, A. Shan, X. Dong, J. Wu // J. Alloys Compounds. – 2008. – 462, № 1-2. – Р. 436–441. doi:10.1016/j.jallcom.2007.08.064

  3. Parthasarathy T.A., Mendiratta M.G., Dimiduk D.M. Oxidation mechanisms in Mo-reinforced Mo5SiB2(T2)-Mo3Si alloys // Acta Materialia. – 2002. – 50, № 7. – P. 1857–1868. doi:10.1016/S1359-6454(02)00039-3

  4. Сенюшкин Н.С. Способы повышения эффективности энергоустановок на базе ГТД // Молодой ученый. – 2011. – 1, № 7. – С. 53–55.

  5. Kruzic J.J., Schneibel J.H., Ritchie R.O. Ambient-to elevated-temperature fracture and fatigue properties of Mo-Si-B alloys: role of microstructure // Metallurg. Mater. Trans. A. – 2005. – 36, № 9. – P. 2393–2402. doi:10.1007/s11661-005-0112-5

  6. Криклива І.Ю., Дудка О.І., Хальмаер M. Сплави системи Mo-Si-B // Фізика і хімія твердого тіла. – 2011. – 12, № 2. – С. 365–369.

  7. Nowotny H., Dimakopoulou E., Kudielka H. Untersuchungen in den Dreistoffsystemen: Molybdän-Silizium-Bor, Wolfram-Silizium-Bor und in dem System: VSi2−TaSi2 // Monatshefte für Chemie. – 1957. – 88, № 2. – S. 180–191. doi:10.1007/BF00901624

  8. Mechanically alloyed Mo–Si–B alloys with a continuous a-Mo matrix and improved mechanical properties / M. Krüger, S. Franz, H. Saage et al. // Intermetallics. – 2008. – 16, № 7. – P. 933–941. doi:10.1016/j.intermet.2008.04.015

  9. Perepezko J.H., Sakidja R., Kim S. Phase stability in processing and microstructure control in high temperature Mo-Si-B alloys // MRS Proc. – Warrendale, 2000. – 646. – P. 253–259. doi: 10.1557/PROC-646-N4.5.1

  10. Loboda P.I. Features of structure formation with zone melting of powder Boron-containing refractory materials // Powder Metallurgy and Metal Ceramics. – 2000. – 39, № 9-10. – P. 480–486. doi:10.1023/A:1011322707881

  11. Crystal structure and physical properties of Mo2B: First-principle calculations / D. Zhou, J. Wang, Q. Cui, Q. Li // J. Appl. Phys. – 2014. – 115, № 11. – P. 113504. doi:10.1063/1.4869055

  12. Ashbrook R.L. Directionally solidified ceramic eutectics // J. Amer. Ceramic Soc. – 1977. – 60, № 9-10. – P. 428–435. doi:10.1111/j.1151-2916.1977.tb15527.x

  13. Llorca J., Orera V.M. Directionally solidified eutectic ceramic oxides // Progress Mater. Sci. – 2006. – 51, № 6. – P. 711–809. doi:10.1016/j.pmatsci.2005.10.002




DOI: http://dx.doi.org/10.20535/1810-0546.2016.2.59788

Refbacks

  • There are currently no refbacks.