Impact of Particle Size Distribution for Variable Mixing Time on Mechanical Properties and Microstructural Evaluation of Al-Cu/B4C Composite

Abstract

Abstract In the present work the combined effects of particle size and distribution on the mechanical properties of the 20vol.% B4C particle reinforced Al–Cu alloy composites by powder metallurgy is investigated. The aim of this work was to evaluate the effect of mixing time (5h, 15h and 25h) and particle size (23µm and 67µm) of B4C particles on the metallurgical and mechanical properties. It has been found that small ratio between matrix/reinforcement particles sizes resulted in more uniform distribution in the matrix. The particles distributed more uniformly in the matrix with increasing in mixing time. The results also showed that homogenous distribution of the B4C particles resulted in higher hardness, ultimate tensile strength, yield strength and elongation. Fracture surface observations showed that the dominant fracture mechanism of the composites with small B4C particle size (23µm) is ductile fracture of the matrix, accompanied by the “pull-out” of the particles from the matrix, which is attributed to positive effect of reinforcement particles in resistance to the movement of dislocations while the dominant fracture mechanism of the composites with large B4C particle size (67µm) is ductile fracture of the matrix, accompanied by the B4C particle fracture