A new in situ composite fabricated by powder metallurgy with aluminum and nanocrystalline ZrO2 particles

An in situ formed fine needle-like Al3Zr phase reinforced aluminum composite was fabricated by powder metallurgy followed by hot extrusion and hot rolling. The fine Al3Zr phase is the main reinforcement, which distributes uniformly and is oriented in the rolling direction in the hot-rolled composites. A very fine matrix structure with an average grain diameter of 1 μm was also formed in this composite. This composite showed a high strengthening effect. The tensile strength of the hot-rolled composite is about twice as high as that of the matrix. Because of the extremely fine structure of the composite, a high superplasticity, especially high strain rate superplasticity, is expected to be obtained for this composite.