MICROSTRUCTURAL STABILITY AND STRENGTH OF THE CO,CR-(CR,CO)7C3 IN-SITU COMPOSITE.
Abstract
The effect of elevated temperature isothermal exposure and thermal cycling on microstructural stability and compressive strength of the in-situ rod-like composite Co,Cr(Cr,Co)7C3 (Vf approx. 0.3) has been examined. Microstructures were characterized by optical and electron metallography, x-ray point analysis and electron diffraction. Strength was evaluated in compression at ambient and elevated temperatures. Changes in microstructure with post-solidification treatments are shown to arise from a combination of precipitation and dissolution of (Co,Cr)23C6, rounding and splitting of the primary (Co,Cr)7C3 fibers, spheroidization of constituents and void formation at fiber-matrix interfaces. The observed strength changes are analyzed in terms of a dispersion-hardening model. Failure in compression below the ductile to brittle transition temperature of the reinforcement occurs by shear in the matrix accompanied by transverse cleavage of the fibers. Above the ductile-to-brittle transition temperature of the reinforcing phase both matrix and carbide exhibit plastic flow. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1979
- Accession Number
- ADA067899
Entities
People
- Alan Lawłey
- H. Saatchi
Organizations
- Drexel University