Microstructure evolution during spray rolling and heat treatment of 2124 Al

Abstract

Spray rolling is a strip-casting technology that combines elements of spray forming and twin-roll casting. It consists of atomizing molten metal with a high velocity inert gas, quenching the resultant droplets in flight, and directing the spray between mill rolls. In-flight convection heat transfer from atomized droplets and conduction heat transfer at the rolls rapidly remove the metal's latent heat. Hot deformation of the semi-solid material in the rolls results in fully consolidated, rapidly-solidified product. Spray rolling operates at a higher solidification rate than conventional twin-roll casting and is able to process a broader range of alloys at high production rates.A laboratory-scale strip caster was constructed and used to evaluate the interplay of processing parameters and strip quality for strips up to 200 mm wide and 1.6-6.4 mm thick. Plans are underway to scale to 600 mm width and demonstrate steady-state operation. This paper describes microstructure evolution during spray rolling. It also examines how the liquid content of the semi-solid material, and post-deposition thermo-mechanical processing, influence the microstructure and mechanical properties of spray-rolled 2124 Al.

Fabrication of Functional Graded Al2124 Composite Reinforced with Al2O3 Particles

“…3 shows that all peaks belong to a regular Al phase. The peaks are in accord with previous reports [10,11]. Because Al alloy was not heat treated, no secondary phase is seen in Fig.…”

Highly tuned gas atomization for controlled preparation of coarse powder

“…Alternatively, gas atomized melt sprays are deposited directly on mandrels or substrates to generate pre-form shapes for deformation processing, where the pre-forms also can benefit from close control of droplet size and solidification microstructure [2]. The study of gas atomization in high temperature, high surface tension fluids (molten metals) often involves complex "two fluid" nozzles to achieve a desirable degree of disintegration (sufficiently fine powder) and an adequate powder or spray production rate.…”

Dry Sliding Wear Behavior of Zircon Sand Reinforced Al–Si Alloy

“…The microstructural refinement and uniformity in distribution of reinforcement in the matrix depend upon melt superheat, nozzle to substrate distance, metal to gas flow rate and high heat removal rate at the droplet-gas interface [4,5]. Further microstructural refinement and reduction in porosity can be achieved by using spray rolling [6], low pressure spray forming [7], and secondary processes like hot rolling or extrusion [2]. Tensile tests at the ambient and elevated temperatures reveal that spray processed Al-Si alloys have better strength and ductility than processed by conventional ingot metallurgy route [8][9][10].…”