Preparation of the high compressive performance special-shaped C_sf/AZ91D composite part using the liquid-solid extrusion following vacuum pressure infiltration process

To meet the increased demand for light-weight and high-performance special-shaped load bearing parts in automotive industry, the short carbon fiber reinforced magnesium matrix composite (C_sf/Mg) part with complex configuration features and abrupt cross-sectional transitions was fabricated by liquid-solid extrusion following vacuum pressure infiltration process (LSEVI). Near-net forming schemes of both the special-shaped fiber preform and composite part were proposed. The effect of process parameters on the forming quality of the composite part was discussed. Meanwhile, the microstructures and compressive properties in different regions of the part were analyzed. The results show that the forward forming scheme provides the special-shaped fiber preform with no surface defects. For the C_sf/AZ91D part, its internal microstructures show that the infiltration of liquid magnesium is sufficient and uniform. The compressive strength of the composite part can reach up to 487 MPa, corresponding to ∼40% increase compared to 335 MPa of the AZ91D alloy. The average compressive strain of composites is less than 10%, which is about 50% of that of the AZ91D alloy. When the fiber orientation is parallel to the shear direction on the shear plane, the load-bearing capacity of the fiber is much higher than that of the fiber perpendicular to the shear direction. This work not only provides a convenient approach to fabricate special-shaped preform with high fiber volume fraction, but also gives a demonstration for the near-net forming of C_sf/Mg parts with excellent material isotropy and compressive properties.