循环加载下铸造铝合金中硅颗粒的破坏行为

Damage Behavior of Eutectic Silicon Particles in ZL101 Aluminum Cast Alloys During Cyclic Loading

摘要:

研究了在等效应变幅为0.22%时ZL101 T6铝合金在单轴、比例、非比例圆形路径下的低周疲劳行为，并用金相显微镜观察了在循环加载条件下硅颗粒的破坏行为.结果表明：在循环加载下，硅颗粒表现出断裂和与铝基体界面分离2种破坏行为，但以断裂方式为主； 硅颗粒的形貌、大小、分布对硅颗粒的断裂行为有重要影响，形貌率大、颗粒长轴方向平行于拉伸轴或位于试样表面、孔洞边沿突起的硅颗粒优先发生断裂；不同的加载路径可改变硅颗粒的断裂方式，在多轴非比例加载下，同一硅颗粒可能会在多个方向上发生断裂，而在单轴或比例加载下一般只能出

Abstract:

Mechanical fatigue tests were conducted on specimens machined from cylindrical cast ZL101 T6 materials with the equivalent strain amplitude of 0.22% under uniaxial, proportional and nonproportional loadings, respectively. Optical microscope was used to examine the damage behavior of eutectic silicon particles when fatigue to any given number of cycles. Particle debonding and cracking are both existence, but the particle cracking takes the primary, especially under multiaxial loadings.The size, aspect ratio and distribution of eutectic silicon particle have great influence on its damage behavior. Enlongated particles with their major axes parallel to the tensile axis, as well as the particles distributed around specimen’s outside surface and pore’s sharp notches, show the greatest tendency to cracking. The cracking modes of particles are affected by the loading path used. Large particles can crack in several different directions under nonproportional loading but always crack in one direction under uniaxial and proportional loadings, which results in faster cracking rate of eutectic silicon particles and shorter fatigue life under multiaxial nonproportional loading.