Extrusion directly following vacuum infiltration is a special forming technique that
combines the advantages of liquid metal infiltration and semisolid extrusion. The major advantages of
this process are elimination of porosity and shrinkage, good surface finish, good dimensional
accuracy, high strength to weight ratio and near net shaping. Magnesium matrix composites are
fabricated usually through stirring casting, powder forming, injecting deposition, liquid metal
infiltration or die casting at present time. However few investigations on magnesium matrix
composite are conducted for the specific characteristics of magnesium alloy, such as high chemical
activity and easy oxidation. The present paper is focused on Csf/Mg composites obtained via
infiltration of porous short carbon fiber preform by liquid Magnesium. The complete experiment
setup is designed and fabricated by ourselves, which include the forming molds, the unit for melting
the magnesium, the unit for vacuuming and the monitoring and collecting system of forming process
parameters. In this method the whole experiment setup is vacuumed firstly. Then the pressurized
nitrogen is used to infiltrate the magnesium melt through a porous preform of short carbon fibers.
After the infiltration completed, the punch of the press extrude the magnesium-infiltrated preform out
of the forming die to form the tubes or bars. X-ray diffraction (XRD), optical and SEM microscopes
were used to characterize the infiltration and the microstructure of fabricated composites. The
compression test was used to characterize the mechanical properties of fabricated composites. The
results show that the preform was infiltrated thoroughly by melt magnesium and the fabricated Csf/Mg
composites have excellent mechanical properties compared with the magnesium alloys. Csf/Mg
composites should be very promising candidates for automobile parts and portable electronic
appliance parts in the future.
Kinetics of liquid metal infiltration in TiC-SiC or SiC porous compacts
