Effects of rolling on microstructures and properties of in-situ (TiB2 + ZrB2)/AlSi9Cu1 composites

In this paper, the (TiB2 + ZrB2)/AlSi9Cu1 composites were fabricated via in situ reaction from Al-K2TiF6-K2ZrF6-KBF4 reaction system. The effects of rolling on microstructures and properties of the composites were investigated by XRD, SEM, TEM and mechanical tensile test. In addition, the influence mechanisms of plastic deformation on aluminum alloy composites were discussed in detail. The results show that the in situ TiB2 and ZrB2 particle well distributed in the matrix with the size of 20 similar to 50 nm and the morphology is short-stick or plate. The rolling technology could obviously optimize the microstructure, enhance the properties of the composite especially, after 6 passes hot rolling and 4 passes cold rolling, the TiB2 and ZrB2 particles clusters with size range from 80 to 150 nm were uniformly distributed in the matrix, the Si phases were fractured into different small parts with the size of less than 1 mu m and the grains size were further reduced. The ultimate tensile strength (UTS) and elongation (EL) of in situ composite are 282 MPa, 17.6%, respectively. Also, the Portevin-Le Chatelier (PLC) phenomenon found in the composite was discussed.