Mechanical properties of Al-60 Pct SiC<Emphasis Type="Italic">p</Emphasis> composites alloyed with Mg

In the present work, the effect of an Mg addition on the mechanical properties of the Al-60 vol pct SiCp composites were investigated by uniaxial compression, three-point bending, impact and wear tests (composite-metal and composite-abrasive types). The composites were produced by the pressure-infiltration technique. The composition of the Al matrix was varied between 0 and 8 pct Mg. The mean diameter of the SiC particles was 23 μm. Upon addition of Mg, Mg₂Si precipitated in the matrix and the amount of the porosity dramatically decreased. Mg-alloyed-matrix composites exhibited higher strength, lower toughness, and higher wear resistance than pure-Al-matrix composites. During composite-metal wear testing, wear progressed in two sequential periods (running-in and steady state). Weight loss during wear testing decreased with increasing Mg content of the matrix. The degree of improvement of abrasive resistance depended on the abrasive-grain size. Above 200 °C, the composite-abrasive wear resistance decreased with increasing test temperature for all materials.