Effects of Zn addition on the microstructure and tensile properties of hot-extruded Al-16 wt% Al4Sr in-situ composite

In current research, the effects of Zn addition (3-15 wt%) on the microstructure and tensile properties of hot-extruded Al-16 wt% Al4Sr composite have been investigated. Microstructural examinations were assessed by the use of scanning electron microscopy and energy dispersive spectroscopy. The results showed that Zn addition improves tensile properties and the mechanism responsible for this progress is solid solution strengthening. Tensile testing of the hot-extruded Al-16%Al4Sr composite revealed that the addition of 15 wt% Zn to the composite improves ultimate tensile strength (UTS) from 179 MPa to 220 MPa, but reduces elongation percent. Moreover, hot extrusion was found to be powerful in refining coarse intermetallics and achieving microstructural uniformity apart from reducing porosities, which all result in toughness enhancement. The study of fracture surfaces of all hot-extruded MMCs revealed that the ductile mode of fracture is dominant. (C) 2014 Elsevier B.V. All rights reserved.