The Magnesium Research Group was established for an IIOF project. Collaborations with the Light Metal Research Centre and overseas universities assist the group to focus on magnesium alloy research to create business potential in New Zealand.
Magnesium is the third most commonly used structural metal, following steel and aluminium. Magnesium, in its purest form, can be compared with aluminium, and is strong and light, so it is used in several high volume part manufacturing applications, including automotive and truck components.
The second application field of magnesium is electronic devices. Due to low weight, good mechanical and electrical properties, magnesium is widely used for manufacturing of mobile phones, laptop computers, cameras, and other electronic components.
Historically, magnesium was one of the main aerospace construction metals and was used for German military aircraft as early as World War I and extensively for German aircraft in World War II. The Germans coined the name 'Elektron' for magnesium alloy which is still used today.
Due to perceived hazards with magnesium parts in the event of fire, the application of magnesium in the commercial aerospace industry was generally restricted to engine related components. Currently the use of magnesium alloys in aerospace is increasing, mostly driven by the increasing importance of fuel economy and the need to reduce weight. The development and testing of new magnesium alloys continues.
Many attributes make the use of magnesium attractive, the most important of which has always been the light weight, with a density only two-thirds that of aluminium and one-quarter that of steel. However, a number of other positive attributes that may be less appreciated further enhance the benefit of magnesium use:
- Strength: static and dynamic properties compare favourably with competitive materials. Specific strength is better than most other engineering materials or plastics. Specific stiffness is greater than all other common engineering materials. Many alloys have better temperature stability than aluminium alloys.
- Damping: some alloys have extremely high damping capacity. Some gravity cast alloys are used for vibration free platforms in metrology and satellite applications. Even commercial die cast magnesium alloys have better damping than competitor materials such as steel or aluminium. Coupled with low weight and inertia, this reduces vibration and resonance in moving parts, e.g. reduced noise and vibration in automotives. One example of this is the now almost universal use of die cast magnesium alloy cores for vehicle steering wheels.
- Castability: most alloys have excellent castability and uniformity of properties in various section thicknesses and can be cast by all current casting processes.
- Formability: although magnesium is relatively difficult to form at ambient temperatures, at elevated temperatures it can be easily rolled to plate and thin sheet or extruded, forged or pressed to intricate profiles
- Machinability: alloys can be machined faster than any other engineering metal. Magnesium can be machined dry or with compatible standard coolants. Chips, etc., can be recycled in volume production.
- Weldability: most alloys are weldable by conventional argon arc [metal inert gas (MIG)/ tungsten inert gas (TIG)] techniques. They are also amenable to laser welding, friction stir welding and other state of the art techniques.
- Corrosion: untreated magnesium is more corrosion resistant than steel in normal environments. Modern high purity alloys have corrosion resistance comparable with conventional aluminium alloys. For more severe environments, effective protection measures are necessary.
- Recycling: scrap and components can be recycled to the same high purity and quality standards as primary alloy. Long term use therefore has minimal environmental impact and significant energy savings, which are key factors for use in transport and commercial applications
- Availability: magnesium is the sixth most abundant element and readily exploitable. Resources are available worldwide. Most widely used sources are magnesite (MgCO3), dolomite (MgCO3.CaCO3 ), carnallite (KCl.MgCl2.6H2O) and various MgCl2 containing brines, including sea water, which contains ,1.1 kg m23 Mg even before concentration. Most of these sources can be converted to magnesium leaving only non-toxic and nonpolluting byproducts. Even minerals such as serpentine from asbestos tailings can be efficiently exploited.
- Mg alloy development: Focusing on alloys of Mg-Sn, Mg-RE systems with improved creep resistance, and computer thermodynamic modelling on new Mg alloys
- Mg processing: Superplastic deformation, heat treatment and thermo-mechanical treatments to improve properties of Mg alloys. Studies on the partial melting zone in arc welding of Mg-Al alloys
- Coating II: Research on the electrothermical deposition on Mg, focusing on electroless plating, electro-plating, conversion coatings, micro-arc oxidation, cermaic PVD/CVD thin films and magnetron sputtering