Qualitative and quantitative assessment of microstructure in Al-B4C metal matrix composite processed by modified stir casting technique

• Al-B4C composites containing 5–20 wt.% B4C were produced by modified stir casting.
• Modified stir casting produced uniformly dispersed B4C reinforcement in Al matrix.
• SEM study revealed good interfacial bonding between B4C particle and Al matrix.
• Agglomeration, homogeneity and randomness of particles were quantitatively investigated.
• Microhardness was investigated as a function of varying indentation load.

Recently, boron carbide reinforced aluminum matrix composites have witnessed an unprecedented technological significance as a structural neutron-shielding material for nuclear waste and nuclear submarines. The present study deals with processing of 6061Al-B4C composites containing different wt.% of B4C using modified stir casting method with bottom pouring arrangement. The dispersion of B4C particles in the aluminum matrix, interfacial characteristics and microstructural features were qualitatively characterized using field emission scanning electron microscope (FESEM) and optical microscope. Microstructural characterization revealed that the dispersion of B4C particles in the matrix was relatively uniform and at some locations small scale agglomeration and clustering of particles were observed. Particle size distribution has been studied for the quantitative description of agglomeration of B4C particles in the matrix which reveals the presence of small scale agglomeration of particles. Homogeneity and randomness of B4C particles in the matrix has been calculated by quadrat method. The results show a random spatial distribution of particles with small scale clustering. Microindentation test were performed on the fabricated composite and obtained results were statistically evaluated.