Al－Al_3Ni自生复合材料的高周疲劳损伤断裂机制及其应力比的影响

HIGH CYCLE FATIGUE DAMAGE AND FAILURE MECHANISMS OF Al Al 3Ni IN SITU COMPOSITES AND INFLUENCE OF STRESS RATIO

实验观察和研究了Ａｌ－Ａｌ３Ｎｉ自生复合材料的高周疲劳损伤断裂行为以及应力比Ｒ的影响，结果显示在Ｒ＝－１疲劳过程中孔洞沿界面区基体的优先萌生、联接和扩展是其损伤断裂的主要机制；并且发现Ｒ对疲劳寿命及断裂过程有明显影响，当Ｒ＝０时滑移带裂纹生长相对容易，寿命减小，而Ｒ＝∞时，裂纹集中在类似于压缩变形的宏观形变带内发展。

The high cycle fatigue fracture behavior of Al Al 3Ni in situ composites, with stress ratio R=-1, 0, ∞ respectively, was observed and investigated. It is shown in the fatigue specimens with R=-1 that microvoids are formed, linked up with each other and result in cracks growing along the interface zone in matrix preferentially, which is the controlling damage and failure mechanism. It is also found that the influence of stress ratio on the high cycle fatigue life and fracture process is very significant. For the fatigue specimens with R=0 ,the micro cracks are preferably growing in slip bands, and the fatigue life drops remarkably. For the fatigue specimens with R=∞ , however, the growth of micro cracks is concentrated in the deformation bands which are similar to those in compression, and the fatigue life is very high.