基于轻质、高强和耐磨等诸多优势，铝基碳化硼复合材料已成为集结构/功能一体化的新型材料。本文采用粉末冶金及轧制方法，制备出厚度3.5 mm、碳化硼质量分数为33%的B4C/Al复合材料板材，并对其疲劳性能和断裂机制进行分析。在1×107循环次数下，铝基碳化硼复合材料板材的疲劳强度达到110 MPa。采用SEM对疲劳断口进行观察，结果表明B4C/Al复合材料疲劳断口可清楚的看到裂纹的萌生、扩展和失稳断裂的典型特征，但存在多种形式的疲劳启裂源。疲劳裂纹扩展路径取决于裂纹尖端塑性区的半径和B4C颗粒的间距大小，当增强颗粒的间距小于塑性区半径时，裂纹主要沿着颗粒的连接界面或断裂的碳化硼颗粒扩展，当增强颗粒的间距大于塑性区半径时，有利于裂纹尖端钝化，减缓裂纹的扩展和方向改变。%With the advantages of low density, high strength and wear resistance, etc, the aluminum matrix composite reinforced by ceramic particles has became a new material which integrating structure and function. The B4C/Al composite with mass fraction of 33% of boron carbide and the plates of thickness 3.5 mm were manufactured by powder metallurgy and rolling. The fatigue performance and fracture mechanism of B4C/Al composite were studied. Fatigue experiment concludes that the fatigue limit of B4C/Al composite is 110 MPa under 1×107 fatigue cycles. SEM and EDS were used to observe the fatigue fracture and analyze the fracture points. The characteristics of crack initiation, crack propagation, unstability to breakdown were found on the fatigue fracture surface, and different kinds of fatigue source exist in the B4C/Al composite; The fatigue crack extension path of B4C/aluminium composites with a high content of boron carbide depends on the particle interval of B4C and radius of the crack tip plastic zone. When the radius of crack tip is bigger than the interval between B4C particle, the fatigue crack extends mainly along the grain interface of particles and fracture surface of B4C particles. Otherwise, the passivating of the crack tip leads to slowing down the propagation of the crack and changing the crack propagation direction.
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