Fragmentation Behavior of Al₃Ti Platelet Particles in Al-Al₃Ti Composite by Multi-Directional Forging

Abstract

When an Al-Al₃Ti composite containing platelet Al₃Ti particles is severely deformed, distribution and size of the Al₃Ti particles are drastically changed. In this study, distribution change of the Al₃Ti particles in the Al-Al₃Ti composite by multi-directional forging (MDF) is investigated. The Al₃Ti particles are fragmented and refined with increasing number of MDF passes. As well as particle size, shape of Al₃Ti particles changes from platelet to granular. Moreover, deviation of Al₃Ti particle-size distribution gets smaller as the number of MDF passes increases. In order to investigate change of the spatial-distribution of the Al₃Ti particles by MDF, the spatial particle distributions of Al₃Ti particles in the Al-Al₃Ti composite deformed by MDF are evaluated by Morisita's index I_δ. As a result, the fragmented Al₃Ti particles form aggregation at 3 passes of MDF. In addition, shape of the aggregation of the Al₃Ti particles is similar with that of the Al₃Ti particles in undeformed Al-Al₃Ti composite. This phenomenon can be explained by plastic flow of matrix during the MDF.