Microstructure and mechanical properties of Al-7075/B₄C composites fabricated by plasma activated sintering

In this work, we prepared Al-7075/B₄C composites by milling powder mixtures using a shaker-mixer mill, sintering the milled mixtures using plasma activated sintering (PAS), and heat treating the sintered product. To characterize the microstructure of the composites, we used field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Al-7075/B₄C composites can be prepared by PAS with high relative densities at low temperature. Increasing the B₄C content increased the hardness, bending strength, and compressive yield strength of the composite. However, adding too much B₄C caused B₄C agglomerates to form, decreasing the hardness and bending strength of the composite. At 7.5 wt.% B₄C, the Vickers hardness, bending strength, and compressive strength of the consolidated samples were 184.3 HV, 813 MPa, and 895 MPa, respectively. We attributed these superior mechanical properties to good interfacial bonding between the matrix alloy and the reinforcement.