Another CSIRO project is also pushing back the frontiers of magnesium applications. Dr Colleen Bettles and colleagues at the Cooperative Research Centre for Cast Metals Manufacturing (CAST), in partnership with the Australian Magnesium Corporation, have developed AMC-SC1, a magnesium alloy that they expect to be part of the next breakthrough for engine design and manufacturing.
Magnesium Engine Blocks the Next Stage of Materials Evolution
Magnesium alloy engines are likely to be the next step in the quest for lighter internal combustion engines. Aluminium alloys that could cope with the high temperatures and high mechanical stress demands of internal combustion engines were developed nearly 50 years ago. For some decades they have been slowly replacing cast iron, and have enabled the production of engine blocks that weigh around 66% less than cast iron blocks. The aluminium alloys were a major breakthrough but magnesium takes this weight reduction further, creating engine blocks that are around 75% lighter than those made of cast iron.
Advantages of Magnesium Alloys over Aluminium Alloys
Magnesium alloys are not only lighter but have other benefits, such as high shock and dent resistance, and a greater ability than aluminium to dampen noise and vibration.
Why Focus So Much Attention on Engine Blocks?
‘Losing weight can help cars reduce both fuel consumption and greenhouse gas emissions,’ says Professor David St John, CEO of CAST. ‘The heaviest part of a car is its engine, and the engine block makes up to 20-25% of the engine weight. Developing a magnesium alloy that can be used in the high-temperature conditions found in modern car engines has been the goal of researchers for many years.’
AMC-SC1 A New Magnesium Alloy for Engine Blocks
It proved to be a major challenge developing a magnesium alloy that had the necessary thermal and mechanical properties, but the new alloy (AMC-SC1) developed by Dr Bettles and colleagues has both alloy content and heat-treatment conditions optimised for performance and cost. The alloy can be prepared and processed using standard techniques, and is suitable for the production of precision castings using a standard sand casting process.
Practical Testing of the AMC-SC1 Magnesium Engine Block
More recently, AVL List, a leading European engine design company, has designed a three cylinder diesel engine with a magnesium block weighing 14kg. This has been fitted into a Volkswagen Lupo and is currently being road tested in and around Graz, Austria. The magnesium engine block could soon become as common as alloy wheels in the list of desirable attributes for new vehicles.