Air-atomised pure aluminium powder with additions of 12.5at%, 37.5at% and 62.5at% of B 4 C was mechanically alloyed (MAed) by using a vibrational ball mill, and MAed powders were consolidated into bulk materials by a spark plasma sintering (SPS) process. Solid-state reactions of the MAed powders during heat treatments were examined by X-ray diffraction (XRD), and mechanical properties of the MAed powder obtained under various heat treatment conditions and those of the SPS materials were evaluated by hardness tests. The solid-state reactions occurred among pure aluminium, B 4 C and stearic acid, added as a process control agent (PCA), after heating at 673K to 873K for 24h to form AlB10, Al3BC and γ-Al2O3. The products obtained by solid-state reactions have affected the Vickers microhardness of the heat-treated MAed powders. The near full density was obtained for the SPS materials under the conditions of an applied pressure of 49MPa at 873K for 1h. The Al–12.5B 4 C SPS material from 16h MAed powder exhibited the highest hardness value of 210HV in the as-fabricated state.