The influence of Ni addition and hot-extrusion on the microstructure and tensile properties of Al-15%Mg<inf>2</inf>Si composite

Publication Type:
Journal Article
Citation:
Materials and Design, 2013, 46 pp. 381 - 390
Issue Date:
2013-04-01
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The effects of nickel addition and hot-extrusion on the microstructure and tensile properties of in situ Al-15%Mg 2 Si composite specimens have been investigated. Al-15%Mg 2 Si composite ingots were prepared by an in situ process and different amounts of nickel (0.1, 0.3, 0.5, 1.0, 3.0 and 5.0wt% Ni) were added to the remelted composite. Optical microscopy (OM) and scanning electron microscopy (SEM) indicated that Ni addition changes the morphology of both primary and eutectic Mg 2 Si phases and decreases the size of primary Mg 2 Si particles from 42μm to 17μm. Hot-extrusion was found to be powerful in breaking the eutectic network and changing the size and morphology of pseudo-eutectic Mg 2 Si phase. The results obtained from tensile testing revealed that both Ni addition and hot-extrusion process improve ultimate tensile strength (UTS) and elongation values. Fracture surface examinations revealed a transition from brittle fracture mode in as-cast composite to ductile fracture in hot-extruded composite after Ni addition. This can be attributed to the changes in size and morphology of primary and eutectic Mg 2 Si phases and also the formation of more and finer α-Al phase. © 2012 Elsevier Ltd.
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