| Air-atomized pure aluminium powder with additions of AlB2 (Al100-x(AlB2)x: x=15, 30, 50) was mechanically alloyed (MA) by using a vibrational ball mill, and MA powders were consolidated by spark plasma sintering (SPS) process. Mechanochemical reactions among pure Al, AlB2 and stearic acid added as a process control agent (PCA) during MA process and subsequent heat treatments were investigated by X-ray diffraction. The hardness of MA powders under various heat treatment conditions was measured. The mechanical properties of the SPS materials were evaluated through hardness and compression tests. Mechanochemical reactions occurred between the MA powders and PCA after heating from 673 to 873K for 24h. Formation of ternary Al3BC compound and γ-Al2O3 was observed in the Al-AlB,sub>2 MA-powders. The hardness of MA powders was increased dramatically after 4h milling time, and a steady increase was observed up to 64h. The Al50(AlB2)50 powder after 64h milling time reached a hardness value above HV400. No significant softening was observed in the MA powders after heating from 573 to 873K for 24h. Full density was obtained for the SPS materials, processed from 4h or 8h MA powders of Al85(AlB2)15, under the SPS conditions of an applied pressure of 49 MPa at 873K for 1h. The compressive proof strength at room temperature of the Al85(AlB2)15 alloy prepared from the MA4h and MA8h powders was 520 MPa and 620 MPa, respectively. |
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