MICROSTRUCTURES AND TENSILE PROPERTIES OF SPRAY-DEPOSITED HIGH-STRENGTH ALUMINUM-ALLOYS

Spray deposition is a new rapid solidification technique which produce s bulk preforms directly from the melt metals. A spray deposition proc ess was used to develop several high-strength aluminium alloys based o n their commercial chemical compositions. These alloys include 2024 al loy, 7075 alloy and 7075 alloy modified with 1.0% Fe and 1.0% Ni. The deposits possessed rapid solidification microstructure with grain size of about 20 mu m and a relative density of over 94%. The hardening ph ases of the materials in T4 or T6 conditions consisted of supersatured solid solution, stable and unstable ageing precipitates and disperse phases. The formation of the fine distributed disperse phases was due to the addition of iron and nickel to the 7075 alloy. The spray-deposi ted materials exhibited substantial improvement in tensile strengths a nd maintained acceptable ductility when compared to the corresponding ingot metallurgy processed materials.