Commonwealth Scientific and Industrial Research Organisation

Wendy Elizabeth Borbidge

Daniel Dong Liang

Kishore Venkatesan

Michael Edward Kellam

Peter Adrian Lynch

Guangsheng Song

Daniel Raymond East

Ross Victor Allen

An improved magnesium-based alloy for wrought applications is disclosed, including a method of fabricating alloy sheet from said alloy. The improved magnesium-based alloy consists of: 0.5 to 4.0% by weight zinc; 0.02 to 0.70% by weight a rare earth element, or mixture of the same including gadolinium; and incidental impurities. The rare earth element in some embodiments may be yttrium and/or gadolinium. In some embodiments the magnesium-based alloy may also consist of a grain refiner and in some embodiments the grain refiner may be zirconium. In combination, the inclusion of zinc and a rare earth element, into the magnesium alloy may have enhanced capacity for rolling workability, deep drawing at low temperatures and stretch formability at room temperature. The improved alloy may also exhibit increased tensile strength and formability while evincing a reduced tendency for tearing during preparation.

Magnesium-based alloy for wrought applications

A process for the production of magnesium alloy strip, by twin roll casting, includes the steps of passing molten alloy from a source of supply to a feeding device; feeding the alloy from the feeding device through an elongate outlet of a nozzle and a pair of substantially parallel rolls spaced to define a bite therebetween; rotating said rolls whereby alloy is drawn from the chamber through the bite; and flowing coolant fluid through each roll and thereby cool alloy received in the chamber by heat energy extraction by the rolls whereby substantially complete solidification of the alloy is achieved in the chamber prior to alloy passing through the bite as hot rolled alloy strip. Alloy is held at the source at a temperature sufficient to maintain alloy in the feed device at a superheated temperature; a depth of molten alloy is maintained in the feed device at from about 5 mm to about 22 mm above a centerline of the bite in a plane containing the axes of the rolls; and heat energy extraction by the cooled rolls is maintained at a level sufficient to maintain alloy strip issuing from the bite at a surface temperature below about 400&#xb0; C.; whereby the hot rolled alloy strip is substantially free of cracks and has good surface quality.

Twin roll casting of magnesium and magnesium alloys

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Hawthorn, Australia

Wendy Elizabeth Borbidge