Stress-induced damage evolution in cast AlSi12CuMgNi alloy with one- and two-ceramic reinforcements. Part II: effect of reinforcement orientation

While there is a large body of literature on the micromechanical behavior of metal matrix composites (MMCs) under uniaxial applied stress, very little is available on multi-phase MMCs. In order to cast light on the reinforcement mechanisms and damage processes in such multi-phase composites, materials made by an Al-based piston alloy and containing one- and two-ceramic reinforcements (planar-random oriented alumina fibers and SiC particles) were studied. In situ compression tests during neutron diffraction experiments were used to track the load transfer among phases, while X-ray computed tomography on pre-strained samples was used to monitor and quantify damage. We found that damage progresses differently in composites with different orientations of the fiber mat. Because of the presence of intermetallic network, it was observed that the second ceramic reinforcement changed the load transfer scenario only at very high applied load, when also intermetallic particles break. We rationalized the present results combining them with the previous investigations and using a micromechanical model.