Abstract:The mechanical properties of the SiC _w+B₄C_p/MB15 extruded composite made by liquid infiltration technique were tested. It is concluded that the strength and E modulus of the composite are much higher than those of its matrix alloy by analysing its fracture appearance and fracture process observed with SEM; the fracture mode is the combination of cleavage and fibrous mode; cracks pass through whiskers in the fracture process which can be divided into three stages: void initiation, second critical elongation and crack buckling expansion.

Key words: magnesium composites SiC whiskers B₄C particles fracture