Formation, stability, and crystal structure of σ phase in Mo-Re-Si alloys

Journal Article · Fri Jan 01 04:00:00 UTC 2010 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2010.07.020· OSTI ID:988221

Bei, Hongbin ^[1]; Yang, Ying ^[2]; Viswanathan, G. ^[3]; Rawn, Claudia J ^[1]; George, Easo P ^[1]; Tiley, Jaimie ^[3]; Chang, Y. Austin ^[4]

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1. ORNL
2. CompuTherm LLC, Madison, WI
3. Air Force Research Laboratory, Wright-Patterson AFB, OH
4. University of Wisconsin, Madison

The formation, stability and crystal structure of the {sigma} phase in Mo-Re-Si alloys were investigated. Guided by thermodynamic calculations, six critically selected alloys were arc melted and annealed at 1600 C for 150 h. Their as-cast and annealed microstructures, including phase fractions and distributions, the compositions of the constituent phases and the crystal structure of the {sigma} phase were analyzed by thermodynamic modeling coupled with experimental characterization by scanning electron microscopy, electron probe microanalysis, X-ray diffraction and transmission electron microscopy. Two key findings resulted from this work. One is the large homogeneity range of the {sigma} phase region, extending from binary Mo-Re to ternary Mo-Re-Si. The other is the formation of a {sigma} phase in Mo-rich alloys either through the peritectic reaction of liquid + Mo{sub ss} {yields} {sigma} or primary solidification. These findings are important in understanding the effects of Re on the microstructure and providing guidance on the design of Mo-Re-Si alloys.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC); ORNL work for others
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 988221
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 18 Vol. 58; ISSN 1359-6454
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
CRYSTAL STRUCTURE
DESIGN
ELECTRON PROBES
MICROANALYSIS
MICROSTRUCTURE
SCANNING ELECTRON MICROSCOPY
SIMULATION
SOLIDIFICATION
STABILITY
THERMODYNAMICS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION