Age hardening behavior of [AlBO]_W/6061Al composite

6061Al matrix composite reinforced by 20% (volume fraction) Al₁₈B₄O₃₃ whisker ([AlBO]_W/6061Al) was fabricated by a squeeze casting technique. Age hardening behavior of the composite was investigated by means of hardness measurement, DSC and TEM. The results indicate that there are high density dislocations in the matrix of the composite and the grain of the matrix is finer compared with that of the 6061Al. It is also found that the hardness of the composite is much higher than that of the 6061Al, and with increasing aging time after solution treatment, hardness of the composite decreases firstly and then increases until a peak hardness reaches at 8 h aging. The highest hardness of the composite in the solution state is due to the solution strengthening. The decreasing peak hardening effect of the composite compared with 6061Al is caused by the decrease in amount of Mg element, which is resulted from the interfacial reaction between Al₁₈B₄O₃₃ whisker and 6061Al.