In-situ synthesis of MgAl2O4 nanowhiskers reinforced 6061 aluminum alloy composites by reaction hot pressing

In-situ generated MgAl2O4 nanowhiskers, with diameters ranging from 30 to 200 nm, reinforced 6061 aluminum alloy composites have been successfully synthesized by reaction hot pressing under a relatively low temperature (600 °C). The effects of temperature and pressure on the morphology of MgAl2O4 whiskers, as well as microstructure, densification and mechanical properties of the composites were investigated in detail. The results indicate that the MgAl2O4 nanowhiskers with aspect ratio about 10-50 are uniformly distributed and firmly bonded with the matrix. Most of the nanowhiskers acting as bridges penetrate into the Al particles to form a framework bearing and transferring extrinsic loads. The high-resolution transmission electron microscope observation reveals that the MgAl2O4/Al interface is clean, smooth and free from interfacial product, and the whiskers have well-bonded interfaces with matrix. Additionally, the composites, prepared by sintering at 600 °C under the pressure of 50 MPa, exhibit the optimal performance.