B_4C粒度配比对B_4C-Al复合材料显微组织与力学性能的影响

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

在B4C预烧体中真空熔渗铝制备B4C-Al复合材料,研究不同粒度配比对复合材料显微组织和力学性能的影响。结果表明:B4C-Al复合材料主要由B4C、Al、AlB2和Al3BC等相组成;随着细颗粒B4C(d50=1μm)含量的增加,复合材料的HRA硬度逐渐降低,抗弯强度逐渐增大,断裂韧性先增大后稍微降低,当细颗粒B4C含量为40%(质量分数)时,复合材料的气孔率、硬度HRA、抗弯强度和断裂韧性分别为1.08%、71.7、505.8MPa和6.41MPa.m1/2;延性铝的加入和细颗粒B4C的增加是造成材料断裂韧性提高的主要原因;随着Al渗入量的增加,复合材料断口中金属撕裂棱及韧窝的比例增加。

B4C-Al composites were prepared by infiltrating aluminum into porous B4C preform in vacuum and the effect of B4C particle size fraction on the microstructure and mechanical properties of composites were analyzed. The results showed that B4C-Al composite is mainly composed of B4C, Al, AlB2 and Al3BC. With increasing the fine particle B4C （d50=1 μm） content, the hardness decreases while the bending strength increases gradually, and the fracture toughness increases first and then decreases slightly. The B4C-Al composite with 40 mass % fine particle B4C 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 B4C content. The tear ridge and dimple on the fracture surface in the B4C-Al composite increase with increasing the infiltrated aluminum content showing inter/transgranular fracture mode.