Re effects on phase stability and mechanical properties of Mo SS+Mo3Si+Mo5SiB2 alloys

Y. Yang; H. Bei; J. Tiley; E. P. George

doi:10.1016/j.jallcom.2012.12.047

Re effects on phase stability and mechanical properties of Mo _SS+Mo₃Si+Mo₅SiB₂ alloys

Y. Yang, H. Bei, J. Tiley, E. P. George

Microstructural Evolution Modeling

Research output: Contribution to journal › Article › peer-review

13 Scopus citations

Abstract

In this paper, we investigate the effects of Re additions on the microstructure and mechanical properties of a ternary alloy with the composition Mo-12.5Si-8.5B (at.%). This alloy has a three-phase microstructure consisting of Mo solid-solution (Mo_SS), Mo₃Si, and Mo ₅SiB₂ and our results show that up to 8.4 at.% Re can be added to it without changing its microstructure or forming any brittle σ phase at 1600 °C. Three-point bend tests using chevron-notched specimens showed that Re did not improve fracture toughness of the three-phase alloy. Nanoindentation performed on the Mo_SS phase in the three-phase alloy showed that Re increases Young's modulus, but does not lower hardness as in some Mo solid solution alloys. Based on our thermodynamic calculations and microstructural analyses, the lack of a Re softening effect is attributed to the increased Si levels in the Re-containing Mo_SS phase since Si is known to increase its hardness. This lack of softening is possibly why there is no Re-induced improvement in fracture toughness.

Original language	English
Pages (from-to)	32-38
Number of pages	7
Journal	Journal of Alloys and Compounds
Volume	556
DOIs	https://doi.org/10.1016/j.jallcom.2012.12.047
State	Published - Apr 15 2013

Funding

This research was sponsored by the Air Force Office of Scientific and Research Contract No. FA 9550-09-C-0048 through the STTR program with Dr. Joan Fuller as the program manager. YY, HB and EPG would like to acknowledge support from the U.S. Department of Energy, Office of Fossil Energy, Advanced Turbines Program.

Funders	Funder number
U.S. Department of Energy
Air Force Office of Scientific Research
Office of Fossil Energy

Keywords

High-temperature alloys
Intermetallics
Mechanical properties
Microstructure
Phase diagrams

Access to Document

10.1016/j.jallcom.2012.12.047

Cite this

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title = "Re effects on phase stability and mechanical properties of Mo SS+Mo3Si+Mo5SiB2 alloys",

abstract = "In this paper, we investigate the effects of Re additions on the microstructure and mechanical properties of a ternary alloy with the composition Mo-12.5Si-8.5B (at.%). This alloy has a three-phase microstructure consisting of Mo solid-solution (MoSS), Mo3Si, and Mo 5SiB2 and our results show that up to 8.4 at.% Re can be added to it without changing its microstructure or forming any brittle σ phase at 1600 °C. Three-point bend tests using chevron-notched specimens showed that Re did not improve fracture toughness of the three-phase alloy. Nanoindentation performed on the MoSS phase in the three-phase alloy showed that Re increases Young's modulus, but does not lower hardness as in some Mo solid solution alloys. Based on our thermodynamic calculations and microstructural analyses, the lack of a Re softening effect is attributed to the increased Si levels in the Re-containing MoSS phase since Si is known to increase its hardness. This lack of softening is possibly why there is no Re-induced improvement in fracture toughness.",

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AU - Yang, Y.

AU - Bei, H.

AU - Tiley, J.

AU - George, E. P.

PY - 2013/4/15

Y1 - 2013/4/15

N2 - In this paper, we investigate the effects of Re additions on the microstructure and mechanical properties of a ternary alloy with the composition Mo-12.5Si-8.5B (at.%). This alloy has a three-phase microstructure consisting of Mo solid-solution (MoSS), Mo3Si, and Mo 5SiB2 and our results show that up to 8.4 at.% Re can be added to it without changing its microstructure or forming any brittle σ phase at 1600 °C. Three-point bend tests using chevron-notched specimens showed that Re did not improve fracture toughness of the three-phase alloy. Nanoindentation performed on the MoSS phase in the three-phase alloy showed that Re increases Young's modulus, but does not lower hardness as in some Mo solid solution alloys. Based on our thermodynamic calculations and microstructural analyses, the lack of a Re softening effect is attributed to the increased Si levels in the Re-containing MoSS phase since Si is known to increase its hardness. This lack of softening is possibly why there is no Re-induced improvement in fracture toughness.

AB - In this paper, we investigate the effects of Re additions on the microstructure and mechanical properties of a ternary alloy with the composition Mo-12.5Si-8.5B (at.%). This alloy has a three-phase microstructure consisting of Mo solid-solution (MoSS), Mo3Si, and Mo 5SiB2 and our results show that up to 8.4 at.% Re can be added to it without changing its microstructure or forming any brittle σ phase at 1600 °C. Three-point bend tests using chevron-notched specimens showed that Re did not improve fracture toughness of the three-phase alloy. Nanoindentation performed on the MoSS phase in the three-phase alloy showed that Re increases Young's modulus, but does not lower hardness as in some Mo solid solution alloys. Based on our thermodynamic calculations and microstructural analyses, the lack of a Re softening effect is attributed to the increased Si levels in the Re-containing MoSS phase since Si is known to increase its hardness. This lack of softening is possibly why there is no Re-induced improvement in fracture toughness.

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KW - Phase diagrams

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