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Monday, May 15, 2006 - 2:00 PM
MPSA062.2

New Magnesium High Strength Wrought and Cast Alloys

P. Lyon, Magnesium Elektron, Manchester, United Kingdom

Currently available wrought Magnesium alloys are predominantly based upon the strengthening effects of Aluminium and or Zinc additions. This provides alloys which have moderate strength compared with many Aluminium alloys. Improvements in Magnesium alloy technology are available and have included alloy development and process development. An example of the latter is Rapid solidification technology whereby >600Mpa tensile strengths can be achieved. These alloys have however not found application because of poor elevated temperature performance and poor fracture toughness.

Recent activities have concentrated on alloy development to improve properties, combined with conventional wrought production technology. A new alloy currently in the development launch phase is Elektron 675. This alloy offers a step change in mechanical properties which are accentuated as temperature of application increases. Above 1200C for example, Elektron 675 can exceed the properties of high strength Aluminium alloy 7075 T6 at only a fraction of the weight. Properties of wrought products often vary with extrusion ratio; this new alloy is no exception. Data is supplied upon the effect of extrusion profile and heat treatment variations.    

Summary data is also provided on the latest elevated temperature cast alloys  


Summary: Magnesium has the significant benefit of light weight, being only 2/3rds the density of aluminium. This presentation focuses on a new high strength wrought alloy – Elektron 675 and makes mention of the latest cast alloys available. The most commonly used wrought Magnesium alloys used are based upon the Mg-Al alloy system, most notably AZ31. This type of alloy has moderate strength, and is limited in capabilities at temperatures above 1200C (2450F). Improvements have been made in alloy technology to improve strength and to some extent elevated temperature capabilities. Despite these improvements, wrought Magnesium alloys cannot compete with higher strength Aluminium alloys, even on a specific property basis. Development work has now yielded an alloy which shows a step change in tensile properties compared with current alloys. This alloy, known as Elektron 675, can now compete with the properties of many aluminium alloys and moves closer to those of higher strength 7000 series alloys. As temperature of testing increases beyond 1200C(2450F) , the strength of Elektron 675 exceeds those of 7075 T6. This makes Elektron 675 a suitable contender for warm to elevated temperature applications where Aluminium alloys possess insufficient properties and use of Titanium results in costly over design.