Microstructures and Mechanical Properties of in-situ V-V3B2 Composites
- ORNL
A series of binary V-B alloys, with compositions spanning the eutectic, were produced by arc melting and drop casting. Microstructural examination revealed that the fully eutectic structure occurs at V-11B rather than V-15B as reported in the V-B phase diagram (all compositions in at.%). The V-11B eutectic was directionally solidified in an optical floating zone furnace, resulting in a composite microstructure consisting of a V matrix and flake or trigonal shaped V3B2 phase. The boride flake spacing ({umlt e}) decreases with increasing growth rate (R), following the relation {umlt e}2.56R=C, where C is a constant. TEM observations showed that the orientation relationship between the V and V3B2 phases is given by: (001)V // (001)V3B2 and (100)V // (100)V3B2. The growth direction and the V/V3B2 interface are parallel to the (001) direction and (100) planes in the two phases, respectively. Tensile tests were used to investigate the temperature dependence of the strength and ductility of the composite. At temperatures to 600 C, the yield strength of the eutectic is about 140 MPa higher than that of a commonly used vanadium solid-solution alloy, V-4Cr-4Ti. Surprisingly, the eutectic shows 5% tensile ductility at room temperature which increases to 10% as the test temperature is raised to 800 C.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 931558
- Resource Relation:
- Conference: 2006 MRS Fall Meeting, Boston, MA, USA, 20061127, 20061130
- Country of Publication:
- United States
- Language:
- English
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