Thermal-expansion behavior of a directionally solidified NiAl-Mo composite investigated by neutron diffraction and dilatometry

Journal Article · Wed Jun 15 04:00:00 EDT 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1929853· OSTI ID:20711751

Bei, H; George, E P; Brown, D W; Pharr, G M; Choo, H; Porter, W D; Bourke, M A.M. ^[1]

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1. Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States) and Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

The thermal expansion of directionally solidified NiAl-Mo eutectic alloys consisting of nanoscale Mo fibers embedded in a NiAl matrix was analyzed by neutron diffraction and dilatometry. From room temperature to 800 deg. C, perpendicular to the fiber direction, the NiAl and Mo phases expand independently with average coefficients of thermal expansion (CTEs) of 16.0x10{sup -6} deg. C{sup -1} and 5.8x10{sup -6} deg. C{sup -1}, respectively. Parallel to the fiber direction, they coexpand up to 650 deg. C with an average CTE of 12.8x10{sup -6} deg. C{sup -1}, but above this temperature the Mo fibers expand more than the NiAl matrix. This anomalous behavior is the result of the load transfer to the Mo fibers when the NiAl matrix softens. The average CTE of the composite parallel to the fiber direction was determined by dilatometry to be 13.0x10{sup -6} deg. C{sup -1}, which is approximately 11% lower than the value predicted by a simple rule of mixtures using the CTEs of the constituent phases.

• OSTI ID: 20711751
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 12 Vol. 97; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
COMPOSITE MATERIALS
DILATOMETRY
EUTECTICS
FIBERS
MOLYBDENUM
NANOSTRUCTURES
NEUTRON DIFFRACTION
NICKEL ALLOYS
REINFORCED MATERIALS
SOLIDIFICATION
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
THERMAL EXPANSION