Effects of test environment and grain size on the tensile properties of L1 sub 2 -ordered (Co,Fe) sub 3 V alloys

Conference · Tue Jan 01 00:00:00 EST 1991

OSTI ID:5197066

Nishimura, C; Liu, C T

The influence of test environment, grain size, and heat treatment on the tensile properties and fracture behavior of L1{sub 2}-ordered (Co{sub 78}Fe{sub 22}){sub 3}V and (Co{sub 85}Fe{sub 15}){sub 3}V alloys was studied at room temperature. The tensile ductility depends strongly on test environments; the elongation decreases in the sequence of oxygen, vacuum, air, and distilled water. The loss in elongation is accompanied by a change in fracture mode from transgranular to intergranular. When tested in oxygen or vacuum, (Co{sub 78}Fe{sub 22}){sub 3}V specimens exhibited predominantly transgranular fracture, while (Co{sub 85}Fe{sub 15}){sub 3}V specimens exhibited essentially intergranular fracture. Grain refinement of (Co{sub 78}Fe{sub 22}){sub 3}V resulted in a ductility improvement in air, while such a beneficial effect of a grain refinement was not observed in (Co{sub 85}Fe{sub 15}){sub 3}V. These results suggest that: (1) (Co,Fe){sub 3}V alloys exhibit a moisture-induced hydrogen embrittlement and (2) grain boundaries are more intrinsically brittle in (Co{sub 85}Fe{sub 15}){sub 3}V than in (Co{sub 78}Fe{sub 22}){sub 3}V. The presence of a brittle hexagonal phase is suggested to be the reason for the observed grain-boundary brittleness in (Co{sub 85}Fe{sub 15}){sub 3}V. 29 refs., 6 figs., 2 tabs.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5197066
• Report Number(s): CONF-910938-7; ON: DE92002332
• Resource Relation: Conference: International conference on high temperature aluminides and intermetallics, San Diego, CA (United States), 17-19 Sep 1991
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COBALT ALLOYS
TENSILE PROPERTIES
IRON ALLOYS
VANADIUM ALLOYS
DUCTILITY
EMBRITTLEMENT
GRAIN BOUNDARIES
GRAIN SIZE
INTERMETALLIC COMPOUNDS
YIELD STRENGTH
ALLOYS
CRYSTAL STRUCTURE
MECHANICAL PROPERTIES
MICROSTRUCTURE
SIZE
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies