ENCYCLOPÉDIE DE LA RECHERCHE SUR L’ALUMINIUM AU QUÉBEC 2013

48 NOUVEAUX PRODUITS ET MATÉRIAUX À BASE D'ALUMINIUM NEW ALUMINIUM BASED PRODUCTS AND MATERIALS Production of Super Strong Aluminum Based Alloys PRODUCTION D’ALLIAGES SUPER RÉSISTANTS À BASE D'ALUMINIUM La production de super forts alliages à base d'aluminium PRODUCTION OF SUPER STRONG ALUMINUM BASED ALLOYS M.F. Ibrahim, A.M. Samuel and F.H. Samuel Université du Québec à Chicoutimi, Québec, Canada, G7H 2B1 1. Introduction The strength and ductility of Al alloys can be enhanced by controlling the alloying element additions and heat treatment conditions applied. An important group of alloys used in aerospace applications are Al-Cu-Mg-Zn alloys. The aim of the present study was to optimize the strength of Al-Cu-Mg-Zn alloys. Several alloys were prepared and tensile test bars were machined to standard dimensions (ASTM B-108) from as-received one-inch thick plates. The samples were then solution heat-treated at 470°C for times up to 48 hrs. The solution heattreated bars were also aged in order to improve the alloy strength through precipitation hardening. The heat-treated sample structures revealed optimized homogeneity. EDS spectra taken from the fracture surfaces of homogenized samples indicated dissolution of Zn, Mg, and Cu in the Al matrix. Ultra-fine dimples were observed caused by the precipitation of a mixture of fine particles, mainly Al2Cu, Mg2Si and MgZn2. By adjusting the chemical composition of the Al-Cu-Mg-Zn alloy, and using proper casting and heat treatment techniques, an alloy strength of ~1GPa with at least 5% elongation could be achieved. Base alloy A, Solution heat treatment (8h @ 470°C) Alloy B, As-received Base alloy A, solution heat treatment + single aging Alloy B, after Aging New alloy, after Homogenization New alloy, after Aging 2. Objectives Production of super strong Al-Cu-Mg-Zn alloys by controlling As-cast structure, 1.Zn,2.Cu,3.Mg,4.Fe-rich SHT structure, dissolution of Zn- and Cu-phases Alloying elements SHT structure, persistence of Fe-rich phases New heat treatment technique 3. Experimental Procedures Average chemical composition (wt%) of the base alloy and the as-received alloy plates (1in thick) Alloy Code/Alloying Elements Si Fe Cu Mn Cr Ni Zn Mg Ti Zr Al A (Base Alloy) 0.17 0.38 1.98 0.33 0.30 0.02 6.42 2.26 0.016 0.21 Bal. B (As-received) 0.10-0.60 0.1-0.8 1.0-4.0 0-0.8 0-0.8 0-0.8 5.0-8.0 2.0-6.0 0-0.20 0-0.4 Bal. Back scattered SEM image, As-cast structure EDS spectrum - AlFeCuZn phase EDS spectrum - AlFeSi phase EDS spectrum -AlZnCuMg phase Optical microscopy Image analysis EPMA/SEM Stretching & Tensile Testing Cracks Microstructure Cutting-Machining Ascast and As-received Heat treatment Melting EDS New alloy, Proposed aging Slip bands plastic deformation Casting Alloying Elements Mohamed Fawzy Ibrahim Agnès-Marie Samuel Fawzy Hosny Samuel Université du Québec à Chicoutimi SHT 485ºC/48h, incipient melting EDS spectrum - AlFeCu phase Mg2Si precipitates New alloy, Proposed aging New alloy, Proposed aging, Max. UTS 4. Results Alloy Code and Condition / Tensile Properties UTS (MPa) A / Solution heat tre ]Y[

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