颗粒增强铝基复合材料疲劳断裂研究

Fatigue Fracture of Particle Reinforced Aluminum Matrix Composites

对粉末冶金法制备的碳化硅颗粒增强铝基复合材料进行了旋转弯曲疲劳试验研究。采用金相显微镜和扫描电镜分别观察了疲劳试验后复合材料纵向显微组织和疲劳断口。通过金相显微镜,观察了增强体颗粒在疲劳循环应力水平下可能的损伤形式。通过疲劳断口观察,分析了断面上不同区域的疲劳裂纹传播特征。结果表明,增强体的加入有效地提高了复合材料的屈服强度、弹性模量和疲劳性能,使复合材料高周疲劳极限提高到约250MPa(1×107循环周次)。复合材料的疲劳损伤随机分布于试样内。断口分析还表明复合材料疲劳同样遵循裂纹萌生,长大,失稳断裂规律,其裂纹起源于铝基体内。加入SiC颗粒减弱或遮盖了疲劳裂纹传播时的晶体学特征,使得复合材料高周疲劳断面没有发现常见的疲劳辉纹。

Rotating bend fatigue properties of particle reinforced aluminum matrix composite manufactured by powder metallurgy were tested. A significant increase of the fatigue limit （250 MPa at 1×10^7 cycles） and elastic modulus and tensile strength in the composites, respect to the matrix alloys, was observed. SEM micrographs of the fatigue fracture surface indicate that process of high-cycle fatigue of composites may be divided into three stages, fatigue crack nucleation, fatigue crack propagation and final fracture. And the fatigue crack origin is inside Al matrix. On the other hand, fatigue striation did not observed on high-cycles fatigue fracture of the composites, it may be owing to SiC particle.