r Peer Review Abstract ： Micron-B4Cp and 2vol% nano-SiCp reinforced 2124Al matrix composites with different B4Cp reinforcement volume fractions (10, 15, and 20 vol%) were fabricated by powder metallurgy. In this study, the microstructure of the B4Cp/SiCp reinforced Al based composites have been analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and its configured energy dispersive spectroscopy (EDS). X-ray diffraction (XRD) was adopted to identify intermetallic phases that were formed during the heat treatment, and the hardness and the electrical conductivity of the composites were investigated using a microhardness and eddy current conductivity tester. The results show that the microstructure of the composites with 10vol% and 15vol% B4Cp is uniform, and the reinforcements (B4Cp and SiCp) are uniformly dispersed in the matrix. When the volume fraction of B4Cp reaches 20%, the reinforcement agglomeration appears. The dislocation density and dislocation enhancement increase with the increase of the volume fraction of B4Cp. The hardness of the material climbs up and then declines, in which the composite with 15vol% B4Cp has the highest hardness of 331.9HV. In addition, the density of composites decreases with the increase of B4Cp content. When the B4Cp content is 15vol%, the compressive strength of the composite reaches the maximum value of 788MPa, in which its fracture strain
