Thermal stress effects in intermetallic matrix composites. Final report

Technical Report · Wed Sep 01 00:00:00 EDT 1993

OSTI ID:5438001

Wright, P K; Sensmeier, M D; Kupperman, D S; Wadley, H N.G.

Intermetallic matrix composites develop residual stresses from the large thermal expansion mismatch (delta-alpha) between the fibers and matrix. This work was undertaken to: establish improved techniques to measure these thermal stresses in IMC's; determine residual stresses in a variety of IMC systems by experiments and modeling; and, determine the effect of residual stresses on selected mechanical properties of an IMC. X ray diffraction (XRD), neutron diffraction (ND), synchrotron XRD (SXRD), and ultrasonics (US) techniques for measuring thermal stresses in IMC were examined and ND was selected as the most promising technique. ND was demonstrated on a variety of IMC systems encompassing Ti- and Ni-base matrices, SiC, W, and Al2O3 fibers, and different fiber fractions (Vf). Experimental results on these systems agreed with predictions of a concentric cylinder model. In SiC/Ti-base systems, little yielding was found and stresses were controlled primarily by delta-alpha and Vf. In Ni-base matrix systems, yield strength of the matrix and Vf controlled stress levels. The longitudinal residual stresses in SCS-6/Ti-24Al-llNb composite were modified by thermomechanical processing. Increasing residual stress decreased ultimate tensile strength in agreement with model predictions. Fiber pushout strength showed an unexpected inverse correlation with residual stress. In-plane shear yield strength showed no dependence on residual stress. Higher levels of residual tension led to higher fatigue crack growth rates, as suggested by matrix mean stress effects.

• Research Organization: General Electric Co., Cincinnati, OH (United States)
• OSTI ID: 5438001
• Report Number(s): N-94-16518; NASA-CR-191191; E-8127; NAS-1.26:191191; CNN: NAS3-25790; RTOP 510-01-50
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
MATRIX MATERIALS
THERMAL STRESSES
REINFORCED MATERIALS
ALUMINIUM OXIDES
FIBERS
INTERMETALLIC COMPOUNDS
NICKEL BASE ALLOYS
PROGRESS REPORT
SILICON CARBIDES
TENSILE PROPERTIES
TITANIUM BASE ALLOYS
TUNGSTEN
ALLOYS
ALUMINIUM COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
DOCUMENT TYPES
ELEMENTS
MATERIALS
MECHANICAL PROPERTIES
METALS
NICKEL ALLOYS
OXIDES
OXYGEN COMPOUNDS
SILICON COMPOUNDS
STRESSES
TITANIUM ALLOYS
TRANSITION ELEMENTS
360603* - Materials- Properties