THE ELEVATED TEMPERATURE REACTIVITY OF BORON-METAL MATRIX COMPOSITE MATERIALS.
Abstract
The reactivity of high strength, high modulus, low density boron filament with a wide variety of metal matrices at temperatures from 300 C to 1000 C for times of several minutes to one hundred hours has been examined. Aluminum and magnesium have been found to be the least reactive of the common aerospace structural metals. Electrodeposition processes for the fabrication of nickel and aluminum composites were developed as were hot pressure bonding techniques for aluminum and magnesium matrix materials. Elevated temperature exposure for as little as one hour at 500 C was shown to significantly degrade the mechanical properties of nickel-boron composites. Degradation in strength for the aluminum and magnesium composites was evident with temperature and with time at elevated temperatures close to matrix melting point. Chromium, silver, aluminum and magnesium were observed to be the best candidates for diffusion barrier protection of boron from reactive metals. No metal barrier materials capable of long-term high temperature stability in contact with boron were discovered. Only magnesium of the studied metals was stable in the liquid form in contact with boron. Magnesium matrix composites demonstrated ideal composite behavior with ultimate failure occurring by shear in the matrix. Uniaxial composite properties for magnesium and aluminum composites exceeded 7075 aluminum, 6A1-4V titanium and ZK60 magnesium alloys by more than 50% on a strength-to-weight basis and had modulus-to-density ratios which were four times those for the conventional alloys. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1967
- Accession Number
- AD0820900
Entities
People
- John A. Alexander