Influence of length-scale on stabilization of boron carbide in Al-based metal matrix composites during plasma activated sintering

We reported an investigation of the influence of length scale on stabilization of boron carbide (B 4 C) during plasma activated sintering. In the current work, AA7075/B 4 C powders containing two types of B 4 C particles (Micro-B 4 C and Nano-B 4 C) were cryomilled for 8 h in liquid nitrogen, respectively. The characterization of as-cryomilled powders indicated that both Micro-B 4 C particles and Nano-B 4 C particles could distribute homogeneously in the matrix. AA7075/Nano-B 4 C powder have a finer particle size and grain size relative to that of the AA7075/Micro-B 4 C powder. The influence of length scale on stabilization of B 4 C particles during plasma activated sintering was investigated in details. The statistical grain diameter analysis from transmission electron microscopy observation revealed that the grain size of AA7075/Nano-B 4 C bulk (~77.4 nm) is finer relative to those of the AA7075 bulk (~193.5 nm) and AA7075/Micro-B 4 C bulk (~184.7 nm). The coupling effect of ex-situ Nano-B 4 C particles and in-situ dispersion particles contribute to the enhancement of the stabilization of the AA7075/Nano-B 4 C bulk.