Phase transformation and mechanical properties of B4C/Al composites

Lamellar constituted with 5, 15, 25 vol.% B4C/Al composites and homogeneous (namely 5, 15, 25 vol.% B4C/Al) composites were fabricated at sintering temperature 680 °C, sintering pressure 30 MPa, and heat preservation period 90 min via vacuum hot-pressing sintering. Another sample constituted with the raw materials of Al sheet and B4C powders has been prepared by the same sintering process to discuss the interface reaction of Al and B4C. In-situ XRD of B4C/Al mixed powders illustrated that the reaction products between Al and B4C were AlB2, AlB12, Al3BC. EDS and EPMA tests have proved that there was an element diffusion existing at the interface of B4C and Al. After sintering, new generation phases AlB12, Al3BC have been detected by SAED analysis of TEM, additionally, the inner microstructure of the lamellar B4C/Al composites was also observed. The results of mechanical properties showed that the lamellar B4C/Al composites possessed the optimal performance of Vicker hardness 116.23 ± 5.25 Hv, bending strength 780.45 ± 12.35 MPa and fracture toughness 12.21 ± 0.23 MPa∙m1/2, which was better than these of homogeneous B4C/Al composites.