Wettability of 2519Al on B4C at 1000–1250 °C and mechanical properties of infiltrated B4C–2519Al composites

The wettability of 2519Al on boron carbide (B4C) was investigated in detail by an improved sessile-drop method at temperature ranging from 1000 to 1250 °C. The interface reactions of B4C–2519Al systems were analyzed by means of scanning electron microscopy (SEM), electron probe X-Ray microanalysis (EPMA) and X-ray diffraction (XRD). Typical flexural strength and hardness of infiltrated B4C–2519Al composites were studied by three-point-bending tests and Rockwell hardness tester. It is found that the wettability and interaction between molten 2519Al alloy and B4C are sensitive to the temperature and contact time. The contact angles significantly decreased and the solid–liquid interaction was more intense as the temperature increased. On the other hand, the formation of various compounds such as Al3BC, Al3B48C2 and AlB2 was identified. Some Al2Cu and Al3Zr phases appeared in the 2519Al drop during cooling, while AlB2 precipitated far away from the 2519Al/B4C interface. Ternary compounds of Al3BC and Al3B48C2, formed along the interface, play a key role in the improvement of wettability of B4C/2519Al. For infiltrated 2519Al–B4C composites, the typical bending strength and HRA are 300.71 MPa and 80.3, respectively. The main fracture way of infiltrated B4C/2519Al is transgranular rupture, which has smooth fracture surface and intrinsic brittle fracture mode.