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

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.