Effect of B_4C Granulometric Composition on Microstructure and Mechanical Properties of B_4C-Al Composites

摘要

B_4C-Al composites were prepared by infiltrating aluminum into porous B_4C preform in vacuum and the effect of B_4C particle size fraction on the microstructure and mechanical properties of composites were analyzed. The results showed that B_4C-Al composite is mainly composed of B_4C, Al, AlB_2 and Al_3BC. With increasing the fine particle B_4C (d_(50)=1 μm) content, the hardness decreases while the bending strength increases gradually, and the fracture toughness increases first and then decreases slightly. The B_4C-Al composite with 40 mass % fine particle B_4C shows the optimmum mechanical properties. The porosity, hardness HRA, bending strength and fracture toughness of the sample were 1.08 %, 71.7, 505.8 MPa and 6.41 MPa·m~(1/2), respectively. It was found that the toughening of the composites is mainly resulted from the addition of ductile aluminum and the increase of fine particle B_4C content. The tear ridge and dimple on the fracture surface in the B_4C-Al composite increase with increasing the infiltrated aluminum content showing inter/transgranular fracture mode.

关键词