Journals →  Tsvetnye Metally →  2020 →  #1 →  Back

ArticleName Effect of heat treatment on the microstructure and phase composition of the (Mo)ss – Mo3Si alloy doped with Y or Sc
DOI 10.17580/tsm.2020.01.10
ArticleAuthor Udoeva L. Yu., Gulyaeva R. I., Chumarev V. M., Larionov A. V.

Institute of Metallurgy at the Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia:

L. Yu. Udoeva, Senior Researcher, Candidate of Technical Sciences, e-mail:
R. I. Gulyaeva, Senior Researcher, Candidate of Chemical Sciences, e-mail:
V. M. Chumarev, Principal Researcher, Doctor of Technical Sciences, e-mail:
A. V. Larionov, Senior Researcher, Candidate of Technical Sciences, e-mail:


This paper describes the results of a study that looked at the effect produced by rare earth metals (REM) – in particular, Sc and Y – on the structural and phase state of high-temperature composite (Mo)ss – Mo3Si and its thermal stability. To obtain sample model alloys, a burden consisting of binary Mo – 15.3 Si% (at.) alloy and inoculants was subjected to vacuum arc melting. With the help of X-ray diffraction, electron microscopy and thermal analysis, the authors analysed the phase composition, microstructure and the distribution of alloying agents in the metal-silicide composites Mo – 14.8 Si – 2.8 REM% (at.). They also analysed phase stability during heat application. It is shown that the binary alloy constitutes a dual-phase in-situ composite with a Mo3Si matrix reinforced with solid solution particles of (Mo)ss. A third structural component can be found in the samples doped with Sc or Y, which is the result of eutectic solidification and originates from Mo3Si and silicides of REMs. Introduction of Sc and Y leads to an increased microstructural dispersion and an increased (Mo)ss/Mo3Si volumetric ratio. An exothermic effect was identified in the range of 810–860 oC during dynamic heating of the Mo – 15.3 Si% (at.) alloy to 1,500 oC (differential scanning calorimetry), which was attributed to the processes of ordering and recrystallization, the intensity of which is less pronounced in the Sc or Y doped samples. Following 100 hours of soaking at 900 oC, the microstructure of the binary alloy became much coarser, and the phase composition and proportions changed. This was observed in both continuous and cyclic (10 10-hour cycles) regimes of heat treatment. It was established that, after cyclic heat application, the doped samples retain their original microstructural dispersion, while only slight changes occur in the continuous heating regime. Consequently, the introduction of around 3% (at.) of Sc or Y in the (Mo)ss – Mo3Si alloy can lead to stabilized structure and phase state of the composite and a stronger resistance to heat, which is a pre-requisite for high-temperature materials.

keywords (Mo)ss – Mo3Si alloys, doping, yttrium, scandium, microstructure, phase composition, heat treatment

1. Jackson M. R., Bewlay B. P., Rowe R. G., Skelly D. W., Lipsitt H. A. High-temperature refractory metal-intermetallic composites. JOM. 1996. Vol. 48, No. 1. pp. 39–44.
2. Bewlay B. P., Jackson M. R., Zhao J. C., Subramanian P. R. A Review of very-high-temperature Nb–silicide–based composites. Metallurgical & Materials Transactions. 2003. Vol. 34A. pp. 2043–2052.
3. Strom E., Eriksson E., Rundlof H., Zhang J. Effect of site occupation on thermal and mechanical properties of ternary alloyed Mo5Si3. Acta Materialia. 2005. Vol. 53. pp. 357–365.
4. Chen H., Ma Q., Shao X., Ma J. et al. Huang B. Microstructure, mechanical properties and oxidation resistance of Mo5Si3–Al2O3 composite. Materials Science & Engineering. 2014. Vol. A592. pp. 12–18.
5. Mitra R. Intermetallic Matrix Composites. Properties and Applications. Chapter 5 – Molybdenum silicide-based composites. Woodhead Publishing. 2018. pp. 95–146.
6. Berkowitz I., Inghram M. G., Chupka W. A. Polymeric gaseous species in the sublimation of molybdenum trioxide. Journal of Chemical Physics. 1957. Vol. 26, No. 4. pp. 842–846.
7. Ashby M. F., Blunt F. J., Bannister M. Flow characteristics of highly constrained metal wires. Acta Metallurgica. 1989. Vol. 37. pp. 1847–1857.
8. Berczik D. M. Method for enhancing the oxidation resistance of a molybdenum alloy, and a method of making a molybdenum alloy. Patent USA, No. 5595616. 1997.
9. Krüger M., Jain P., Kumar K. S., Heilmaier M. Correlation between microstructure and properties of fine grained Mo – Mo3Si – Mo5SiB2 alloys. Intermetallics. 2014. Vol. 48. pp. 10–18.
10. Schneibel J. H., Ritchie R. O., Kruzic J. J., Tortorelli P. F. Optimization of Mo – Si – B intermetallic alloys. Metallurgical & Materials Transactions. 2005. Vol. 36A. pp. 525–531.
11. Choi W. J., Park C. W., Park J. H., Kim Y. D., Byun J. M. Volume and size effects of intermetallic compounds on the high-temperature oxidation behavior of Mo – Si – B alloys. International Journal of Refractory Metals & Hard Materials. 2019. Vol. 81. pp. 94–99.
12. Stringer J. The reactive element effect in high-temperature corrosion. Materials Science & Engineering: A. 1989. Vol. 120-121. pp. 129–137.
13. Kablov E. N., Ospennikova O. G., Vershkov A. V. Rare metals and rare earth elements as materials for high technology of today and the future. Aviatsionnye materialy i tekhnologii. 2013. No. S2. pp. 3–10.
14. Yang T., Guo X., Luo Y. Microstructural evolution of mechanically alloyed Mo – Si – B – Zr – Y powders. International Journal of Refractory Metals & Hard Materials. 2016. Vol. 56. pp. 35–43.
15. Li R., Zhang G., Lee B., Chen X., Ren S. et al. The multi-scale microstructure and strengthening mechanisms of Mo – 12Si – 8,5BxZr% (at.) alloys. International Journal of Refractory Metals & Hard Materials. 2017. Vol. 68. pp. 65–74.
16. Majumdar S., Schliephake D., Gorr B., Christ H.-J., Heilmaier M. Effect of Yttrium Alloying on Intermediate to High-Temperature Oxidation Behavior of Mo – Si – B Alloys. Metallurgical & Materials Transactions. 2013. Vol. 44A. pp. 2243–2257.
17. Choi W. J., Lee S. Y., Park C. W., Byun J. M., Kim Y. D. Effect of titanium addition on mechanical properties of Mo – Si – B alloys. Journal of Refractory Metals & Hard Materials. 2019. Vol. 80. pp. 238–242.
18. Gokhale A. B., Abbaschian G. J. The Mo – Si (Molybdenum-Silicon) System. Journal of Phase Equilibria. 1991. Vol. 12, Iss. 4. pp. 493–494.
19. Rosales I., Schneibel J. H. Stoichiometry and mechanical properties of Mo3Si. Intermetallics. 2000. Vol. 8. pp. 885–889.
20. Christensen N. A. Preparation and characterization of Mo3Si and Mo5Si. Acta Chemical Scandinavica. 1983. Vol. A37. pp. 519–522.
21. Saage H., Krüger M., Sturm D., Schneibel J. H., Heilmaier M. et al. Ductilization of Mo – Si solid solutions manufactured by powder metallurgy. Acta Materialia. 2009. Vol. 57, Iss. 13. pp. 3895–3901.
22. Mousa M., Wanderka N., Timpel M., Singh S., Kru..ger M. et al. Modification of Mo – Si alloy microstructure by small additions of Zr. Ultramicroscopy. 2011. Vol. 111, Iss. 6. pp. 706–710.
23. Mansurova A. N., Larionov A. V., Tyushnyakov S. N., Marshuk L. A. The phase composition and microstructure of Mo – Si alloys produced in a non-equilibrium crystallization environment. Butlerovskie soobshcheniya. 2015. Vol. 43, No. 9. pp. 97–101.
24. Udoeva L. Yu., Chumarev V. M., Larionov A. V., Zhidovinova S. V., Tyushnyakov S. N. Effect of rare earth elements on the structure and phase state of Mo – Si – X (X=Sc, Y, Nd) in situ composites. Perspektivnye materialy. 2017. No. 7. pp. 24–33.
25. NETZSCH Proteus Software. Thermal Analysis. Version 4.8.3.
26. DIFFRACPlus: EVA Bruker AXS GmbH. Ostliche. Rheinbruckenstrae 50. D-76187. Karlsruhe, Germany, 2008.
27. Powder Diffraction File PDF4+ ICDD Release, 2015.
28. Laugier J., Bochu B. LMGP-Suite of Programs for the interpretation of X-ray Experiments. ENSP. Grenoble : Laboratoire des Materiaux et du Genie Physique, 2003.
29. Kotur B. Ya., Bodak O. I. The ternary systems of Sc – Mo – Si and Sc – Mo – Ge at 1,070 K. Metally. 1988. No. 4. pp. 189–192.
30. Bodak O. I., Gorelenko Yu. K., Yarovets V. I., Skolozdra R. V. The crystalline structure and magnetic properties of R2Mo3Si4 (R – Y, Tb, Dy, Ho, Er, Tm) compounds. Neorganicheskie materialy. 1984. Vol. 20, No. 5. pp. 853–855.
31. Udoeva L. Yu., Chumarev V. M., Leontev L. I., Selmenskikh N. I. Structural-phase state of Nb – Si eutectic alloys, doped by yttrium and scandium. Tsvetnye Metally. 2014. No. 8. pp. 59–65.

Language of full-text russian
Full content Buy