Properties of mechanically alloyed P/M composites of Al–Mg2Si–oxide systems

With a purpose of obtaining light-weight materials of high strength, mixture of aluminum powder and Mg2Si powder at the composition of Al–20mass%Mg2Si2 was mechanically alloyed with addition of oxide (Cr2O3, Fe2O3, MnO2) powders. Mechanical alloying was conducted by using an Attritor-type ball mill under argon atmosphere. The mechanically alloyed powders were consolidated to the P/M materials by vacuum hot pressing and hot extrusion. Solid-state reactions during mechanical alloying and subsequent thermomechanical processing were studied. Their structures and mechanical properties were examined and compared with hyper-eutectic Al–Si based P/M materials. All added oxides were decomposed and aluminide compounds were formed during heating of the extruded P/M materials. Mg2Si was only partially decomposed after heating P/M materials. All the P/M materials of Al–Mg2Si–oxide showed high compressive strength above 900 MPa. Among them, the highest strength of 1090 MPa was obtained for Al–Mg2Si–Fe2O3. Even the P/M material of Al–Mg2Si without oxide addition showed compressive strength of 795 MPa. The Al–Mg2Si based P/M materials showed higher compressive strength and higher ductility than hyper-eutectic Al–Si based P/M materials.