加载路径对铝合金疲劳位错结构的影响

Effect of Loading Paths on the Dislocation Structure of Aluminum Alloy Fatigued under Multiaxial Nonproportional Loadings

目的研究铝合金材料在相同等效应力幅、不同非比例加载路径下的多轴疲劳寿命以及疲劳失效试件位错结构,从而明确加载路径对位错结构的影响.方法利用透射电镜分析了不同加载路径下疲劳试样的位错结构特征.结果铝合金多轴非比例加载疲劳寿命变化规律为:圆形路径<正方形路径<矩形路径<椭圆形路径,圆形路径下位错以交叉滑移为典型特征,正方形路径下以单方向的滑移线以及拉长的位错环为典型特征,矩形和椭圆形路径下均以三方向的多滑移为典型结构特征.结论加载路径对疲劳寿命有明显影响,不同加载路径下疲劳试样位错结构不同,质点对位错有较强的钉扎作用,位错以线形平行排列塞积在质点前.

In order to research the effect of loading paths on the dislocation structure of fatigued aluminium alloy, the fatigue life and dislocations of aluminium alloy under different loading paths with the same efficient stress amplitude were studied. The dislocation structure features of fatigued samples under different loading paths were observed by transmission electron microscope. The results indicate that the fatigue life order, from low to high, follows circle path 〈 square path〈 rectangle path elliptical path〈 elliptical path, cross slip is the typical dislocation feature under circle path, but the typical dislocation features under other loading paths are single slip and longed dislocation loop under square path, mult - slip with three directions under rectangle and elliptical paths respectively. The effect of loading paths on fatigue life is remarkable, the dislocation structures are different under different loading paths; the stunting of particles on dislocation is strong, and the parallel dislocation lines pile up around the particles.