Magnesium Research Joe Robson University of Manchester

Key Application Areas Increased future role for Mg in transport (33% lighter than Al) Future vehicle concepts assume greatly increased application of Mg as part of multi-material structure Challenges Making complex shapes using Mg Reducing anisotropy/asymmetry of properties Joining Mg to Al and steel, joining cast Mg alloys Corrosion control (coatings/protection systems) SuperLight Car Magnesium

Mg Research – Current Hot Topics Based on a survey of recent conference proceedings, top research areas for Mg are – Improving low temperature formability (texture control, rare-earth additions etc.) – Alternative production routes (e.g. twin roll casting, advanced casting processes) – Bio-resorbable magnesium alloys for implants – Corrosion control (alloy design and coatings) – Improving strengthening response (improving precipitation hardening...)

International Picture China, Germany, Canada, Australia and US all have major Mg research activities China – National Engineering Research Centre for Magnesium Alloys, Chongqing ~80 academics Germany – Magnesium Innovation Centre (MagIC) ~50 scientists Canada – MagNET. 20 academics from 5 partner universities

UK Picture UK Mg research activity is comparatively small (handful of academics “part time” on Mg) but maintains wide coverage and internationally recognized position Mg research in UK receives ~ 5% of light metals funding Significant Mg activity within: – LATEST 2 programme – Towards Affordable, Closed-Loop Recyclable Future Low Carbon Vehicle Structures (TARF-LCV) – Centre for Innovative Manufacture in Liquid Metal Engineering (LiME) – Doctoral Training Centre in Advanced Metallic Systems (DTC) Most UK Mg research involves collaboration with industry - Magnesium Elektron

Reducing Temperature for Forming Unlike steel/Al magnesium cannot be formed at room temperature (hcp crystal structure) Reducing temperature required to form Mg is critical to economics for automotive sheet – Alloy design, e.g. dilute rare-earth additions – Fundamental understanding of formability in Mg – Alternative processes, e.g. superplastic forming Relevant UK research – Alloy design and fundamentals [Manchester] – Forming trials and alternative processes [Imperial/Warwick] Improved formability with dilute rare-earth additions

Alternative Process Routes Reducing cost of Mg requires using lower cost production route Twin roll casting (TRC) attractive option – Avoids need for large rolling reduction (difficult with Mg) – Potential to maintain randomized (cast) texture in sheet product – Potential to directly form TRC sheet (e.g. with superplastic forming) Research needed to improve consistency, microstructure and properties of TRC-Mg UK active through TRC optimization LiME [Brunel], microstructure and corrosion performance [Manchester] TRC sheet Light further warm rolling Warm forming Direct superplastic forming of TRC sheet

Bio-resorbable Mg Alloys Potential of Mg for bio-resorbable implants has attracted massive new research interest in past ~10 years Magnesium Elektron developed Synermag – first commercial Mg alloy designed for biological applications UK research – Mg alloy optimization and biological performance [Manchester] – Magnesium Elektron in-house activities Magnesium alloy stent

Corrosion Control and Coatings Corrosion control is critical for Mg use Mg corrosion is highly sensitive to impurities (e.g. Fe) – Key concern for recyclability Mg corrodes rapidly in contact with other metals – must be electrically isolated UK research – Fundamentals of corrosion in Mg alloys [Manchester] – Coating and protection systems for dissimilar joints [Manchester] – Effect of recycling/impurities on corrosion [Brunel, Manchester] Corrosion of ZE41 with PEO coating [Manchester] time

Improving Strengthening Response of Mg Highest strength Mg alloys only ~ ½ strength of strongest Al alloy Strongest Mg alloys are precipitation hardened (as with Al) Requires improving effectiveness of precipitates in Mg to provide strength – Fundamentals of strengthening in alloy systems that twin [Manchester] – New alloy systems – Micro-alloying to promote precipitation (as in Al) – Computer based alloy design (ICME) [Manchester]

Other Research Topics Recent/ongoing UK research in – Dissimilar metal joining of Mg to steel, Al structures [Manchester, Warwick] – Magnesium based carbon reinforced composites [Manchester] – Friction stir welding of magnesium [Manchester/Sheffield]