Three-dimensional microstructural analysis of fragmentation behavior of platelet Al3Ti particles in Al-Al3Ti composite deformed by equal-channel angular pressing

Abstract

The fragmentation of platelet Al3Ti particles in an Al-Al3Ti composite by equal-channel angular pressing (ECAP) is investigated using three-dimensional (3D) microstructural evaluation and crystallography. The Al-Al3Ti composite comprises coarse platelet Al3Ti particles in an α-Al matrix. The ECAP of this composite is performed for up to 4 passes under processing routes A, Bc, and C. Route Bc produces the smallest Al3Ti particle fragments in comparison with the fragments produced under routes A and C. This is because that route Bc produces the largest number of shearing directions and shearing planes. Platelet Al3Ti particle fragments in the specimen deformed by ECAP under route A are homogeneously distributed along the deformation axis. In contrast, in the specimens deformed by four ECAP passes under routes Bc and C, the Al3Ti particle fragments are gathered into several groups. The fragment groups have a length similar to the initial length of the platelet Al3Ti particles. These spatial distributions of particle fragments can be explained by material flow of α-Al matrix during ECAP. Moreover, from 3D microstructural evaluation and crystallographic analysis of the Al3Ti particle fragments, it is found that the Al3Ti particles are preferentially fragmented on the twin boundary plane of {112}Al3Ti. Therefore, it is concluded that fragmentation of a platelet Al3Ti particle by ECAP occurs along the twin boundary plane after twin deformation.