(Al2O3)f/Al复合材料在强界面结合下的疲劳损伤模式

在拉-拉载荷下测定了(Al₂O₃)_f/Al复合材料的疲劳寿命(S-N)曲线。通过夭折试验以及SEM疲劳断口和纵截面组织结构分析,研究了复合材料的疲劳损伤模式。研究结果表明,(Al₂O₃)_f/Al复合材料的疲劳极限为750MPa,远高于SCS-6碳化硅纤维增强钛基复合材料。该复合材料兼有钛基和树脂基纤维复合材料疲劳损伤的特点,高应力下由单个裂纹的起源和生长导致复合材料的失效;低应力下,疲劳损伤模式包括纤维劈裂、众多基体裂纹和单个基体裂纹的横向扩展。其中纤维劈裂是主控机制。其更高的疲劳极限可归因于低应力下纤维的纵向劈裂。

FATIGUE DAMAGE MODE OF (Al2O3)f/Al COMPOSITE

The S-N curve of strongly-bonded (Al2O3)f/Al composite wire was determined under tension-tension loading. To understand the fatigue damage mode of the composite, interrupted tests were carried out at different stresses. The fatigue fractograph and microstructures of samples were examined using SEM. The endurance limit of the composite was about 750MPa, which is much higher than about 600 MPa of the SCS-6 fiber reinforced Ti matrix composites. The composite possesses fatigue damage modes of both Ti and resin matrix composites. At high stresses, the initiation and growth of a single crack result in the failure of the composite, while at low stresses the fatigue damage mode includes fiber splitting and transverse propagation of numerous matrix cracks at beginning and single crack propagation at the final stage. The fiber splitting is a controlling mechanism of the composite and the higher endurance limit of the composite can be attributed to it.