The effects of processing on the microstructures and properties of Gr/Mg composites

The microstructures and properties have been investigated in graphite/magnesium metal matrix composites (Gr/Mg MMCs) hybridized and un-hybridized with SiC particles. It was found that the composites with 730°C melt temperature had a higher strength than those with 700°C melt temperature. The strength increased with the preform temperature increasing from 510 to 660°C. However, in the high temperature section (570–660°C) the increasing tendency became smooth. The interface bonded weakly under the lower temperature (510–540°C) and intermediately under the higher temperature (570–660°C). No strong bonding appeared in Gr/Mg MMCs. The increasing of preform temperature improved the composite wetting and benefited the good distribution of the fibers, however it brought some problems such as loose coating, heavily oxidization and increasing twins. The various effects made increasing the preform temperature in the high temperature section not enhance the tensile strength obviously.