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Micro-Mechanisms of Deformation in SiC/Al Composites.
Final rept. 1 Aug 84-31 Aug 87,
GRUMMAN CORP BETHPAGE NY CORPORATE RESEARCH CENTER
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The deformation mechanisms of aluminum matrix composites containing SiC whiskers or particulate were investigated both experimentally and analytically to determine factors critical to their mechanical behavior. The effects of the discontinuous SiC on age-hardening behavior the influence of silicon carbide morphology interactions between SiC dispersoids and matrix precipitates, and dislocations were considered. Two matrix alloys were investigated a solution-hardened 5456 alloy containing no matrix precipitates and a 2124 alloy that could be aged and cold worked to contain different matrix precipitate microstructures and dislocation contents. The influence of SiC on the age-hardening behavior of 2124 was evaluated using differential scanning calorimetry. The precipitation sequence in the composites was found to be very similar to that in SiC-free material prepared by either powder or ingot metallurgy. Both whiskers and particulate increased the quench sensitivity of 2124 by causing the precipitation of GPB zones and S during the quench from solution heat treatment. This effect was independent of quench rate.
APPROVED FOR PUBLIC RELEASE