RESEARCH ON WHISKER-REINFORCED METAL COMPOSITES.
Final rept. Apr 66-Apr 67,
MELPAR INC FALLS CHURCH VA MATERIALS LAB
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Several aluminum-alloy-sapphire-whisker composite systems were investigated. Consolidation by liquid-phase hot pressing developed previously was significantly improved to yield dense composites with aluminum-silicon hypoeutectic matrices. Strengths in excess of 49,000 psi were obtained in biaxially oriented, unworked composites with 20 to 25 vo 1-3 micron whiskers. In general, the percent increase in composite strengths was greater at elevated temperatures than at room temperature. Magnetic alignment of nickel-coated 1-30 micron whiskers resulted in increasing the uniformity of composite properties. Mechanical working of biaxially oriented aluminum-silicon composites was examined. Hot rolling was the only technique found suitable. Reinforcement in worked composites was erratic owing to severe whisker segregation. Sequential deposition of nickel and chromium by vapor plating was developed and optimized. Fabrication of nichrome composites by densification of the coated whisker mats appeared to be promising. However, initial attempts were hampered by incompatibility of available die materials. Author
- Laminates and Composite Materials