High-Temperature Strength and Deformation Behavior ofAI6063/AI-2O-3 Nanocomposite Produced by Mechanical Alloying andHot Extrusion

摘要

Ultrafine-grained (UFG) AI6063 matrix nanocomposites reinforced with nano-size Al-2O-3 were produced by reactive mechanical alloying and hot powder extrusion method. Microstructural studies were performed by transmission electron microscope (TEM) and electron backscatter diffraction (EBSD). Observation of very small regions with high- and low-angle grain misorientation, i.e. grains and subgrains, showed the formation of UFG Al alloy matrix with an average grain size of ~ 0.37 urn. A uniform distribution of alumina particles with an average size of ~ 100 nm was also achieved. Compression test at various temperatures up to 450 °C was carried out to evaluate the high-temperature strength and hot deformation behavior of the nanocomposite. Formation of highly misoriented and equiaxed grains revealed that dynamic recrystallization (DRX) occurred during hot deformation. While geometrical DRX was more effective at lower deformation temperature, discontinuous DRX had the main role in the softening at higher temperatures.