MCROSTRUCTURAL FEATURES AND TENSILE PROPERTIES OFA NANOSTRUCTURED AL6063-AL2Oa NANOCOMPOSITE

A nanostructured Al6063 matrix nanocomposite were produced by reactive mechanical alloying (RMA) of Al alloy powder in a Ar-5vol%. Oz atmosphere followed by hot powder extrusion. Microstructural features were evaluated by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Microstructural studies revealed the formation of ~1 vol.% amorphous Al2O3 nanoparticles (40-100 nm) during RMA that were uniformly distributed through out the Al matrix.The microstructure of the Al alloy consisted of a duplex grain structure of ultrafine grains (100-400 nm) and nanocrystalline grains (<100 nm). The tensile yield and ultimate strength of the nanocomposite was found to be 175 and 12.6% higher than those of coarse-grained Al6063 alloy, respectively. The strengthening mechanisms are discussed based on the dislocation-based models. It is shown that alumina nanoparticles play a significant role on the strengthening of Al6063- Al2O3 nanocomposite via Orowan strengthening mechanism. The fracture surfaces of the nanocomposite material exhibited a combination of dimple and cleavage fracture modes.

کلیدواژه ها:

Al6063-Al2O3 ، Nanocomposite ، Mechanical alloying ، EBSD ، Strengthening mechanism