Abstract
Cryomilled Al 5083-boron carbide (Al-B(4)C) metal matrix composites (MMCs) are of interest due to their light weight and high strength. Cryomilling is a mechanical milling process during which the powder is ball milled in a liquid nitrogen slurry at cryogenic temperatures. In addition to generating nanocrystalline powder, cryomilling breaks up the nascent oxide layer on the as-received Al powder and introduces nitrides into the microstructure. The dispersed nano-metric inclusions enhance the thermal stability of the powder for subsequent consolidation and thermomechanical processing, ensuring the MMC retains an ultrafine grained (UFG) microstructure. In this study, the effect of milling time, B(4)C particle size, and consolidation variables on the microstructure and mechanical properties of consolidated bulk nanocomposites was investigated. Specific attention was placed on the differences resulting from the incorporation of 0.5 mu m and 6 m B(4)C particulates. The relationship between microstructure and mechanical properties of the nanocomposites are discussed.