Design of Al based composites reinforced with in-situ Al2O3, AlB2 and Al13Fe4 particles

Al based composites reinforced with & gamma;-Al2O3, AlB2 and Al13Fe4 particles were synthesized via sintering the Al-2.5Fe2O3-7.5B2O3, Al-5Fe2O3-5B2O3 and Al-7.5Fe2O3-2.5B2O3 systems and hot extruding. The in-situ formed & gamma;-Al2O3 nanoparticles mainly distribute along grain boundaries, while micron AlB2 and Al13Fe4 particles disperse within matrix grains. All of the composites form fiber texture in the longitudinal section, with the average grain size less than 1 & mu;m. The composite synthesized from Al-2.5Fe2O3-7.5B2O3 has the best ultimate tensile strength at a series of temperatures, which can be 460 MPa and 208 MPa at 250 degrees C and 400 degrees C, respectively. It is deduced that the strengthening effect of Al13Fe4 particles is weaker than Al2O3 and AlB2, and the composite of Al-xFe2O3-yB2O3 is supposed promising for application at elevated temperatures.