Magnesium: commodity or exotic?

The structural use of magnesium through the 20th century is briefly reviewed, highlighting fluctuating levels of development and use influenced by military applications in two World Wars. Development of more efficient processes, improved corrosion resistant alloys and availability of lower cost metal now offer potential for major expansion in magnesium consumption in the 21st century. A review of current worldwide use indicates major growth in structural transport applications. Apart from the obvious advantage of light weight, other important attributes making magnesium an attractive contender for transport applications are considered. Requirements for magnesium to compete effectively as a commodity material are reviewed. Key areas for development are commercial transport, aerospace and high performance uses. The most important is commercial transport. Significant developments in alloy technology and applications for die casting are described and more speculative growth in use of wrought components discussed. A similar review and analysis of developments for aerospace and high performance applications is given. Alloys developed and properties achieved differ significantly from those considered for higher volume commercial applications and include highly sophisticated alloying and manufacturing technology. Although the main theme is magnesium's potential as a commodity material, more exotic applications of magnesium alloys are reviewed. These include electrochemical alloys, space and missile applications, composite materials, non-equilibrium alloys and medical uses. Finally, the future priorities for development of technology and applications are examined by reference to a recent UK 'road mapping' exercise, which was in general accord with similar exercises in Japan, Germany and the USA.