Study on the fabrication of Al matrix composites strengthened by combined in-situ alumina particle and in-situ alloying elements

A new idea to fabricate aluminum matrix composites strengthened by combined in-situ particle strengthening and in-situ alloying has been proposed. Following the concept of in-situ alloying and in-situ particle strengthening, aluminum matrix composites reinforced by Cu and α-Al2O3 particulate (material I) and the same matrix reinforced by Cu, Si alloying elements and α-Al2O3 particulate (material II) have been obtained. SEM observation, EDS and XRD analysis show that the alloy elements Cu and Si exist in the two materials, respectively. In-situ Al2O3 particulates are generally spherical and their mean size is less than 0.5 μm. TEM observation shows that the in-situ α-Al2O3 particulates have a good cohesion with the matrix. The reaction mechanism of the Al2O3 particulate obtained by this method was studied. Thermodynamic considerations are given to the in-situ reactions and the distribution characteristic of in-situ the α-Al2O3 particulate in the process of solidification is also discussed.