Superplasticity in a nickel silicide alloy, Ni sub 3 Si (V,Mo)

Technical Report · Sun Dec 01 04:00:00 EST 1991

OSTI ID:5346748

Stoner, S L

The fundamentals of superplasticity, including mechanical and microstructural characteristics are reviewed. The interest in developing intermetallic alloys for high temperature, structural applications is discussed. The superplastic properties of an intermetallic alloy based on nickel silicide have been investigated. A duplex microstructure is shown with a third phase present as dispersions. The {beta} phase is ordered and the ({alpha}+{beta}) phase is a mixture of a solid solution phase and {beta} dispersions. The mechanical behavior of the material is presented. The maximum strain-rate sensitivity is approximately 0.5. The stress/strain curve varies with temperature, strain-rate, and orientation of the tension with respect to the microstructure. Steady-state behavior is shown in Region II as well as strain hardening caused by dynamic growth of the {beta} phase. ({alpha}+{beta}) grains refine with deformation. Growth and refinement are enhanced at slower strain-rates. The nickel silicide alloy cavitates during superplasticity and shows increasing cavitation with decreasing strain-rate. The failure mechanism is intergranular and the final failure occurs by cavity coalescence. Annealing the material prior to testing produced a more uniform microstructure and improve the superplastic performance of the alloy. 43 refs.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5346748
• Report Number(s): UCRL-LR-109425; ON: DE92011651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CRYSTAL STRUCTURE
GRAIN BOUNDARIES
INTERMETALLIC COMPOUNDS
MATERIALS TESTING
MECHANICAL PROPERTIES
MECHANICAL TESTS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
PLASTICITY
SILICON ALLOYS
STRAIN RATE
STRAINS
STRESSES
TESTING
VANADIUM ALLOYS