High Conductivity Mg Alloys

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In competing with aluminium alloys as structural materials, magnesium alloys have the advantages of low density, high strength ratio, better electromagnetic shielding properties and castability. These result in the preferential use of magnesium alloys in components where lightweight and electromagnetic shielding is critical. However, the currently used magnesium alloys have inferior thermal conductivity in comparison with their competitive aluminium alloys. For example, the commonly used AZ91D (Mg-9wt.%Al-1wt.%Zn) magnesium alloy has the thermal conductivity of 51 W/m·K at 20°C and the commonly used A380 (Al-9wt.%Si-3wt.%Cu) aluminium alloy has the thermal conductivity of 108 W/m·K at 20°C. Brunel University has developed a casting magnesium alloy that can provide significantly improved thermal conductivity in comparison to AZ91D. The typical thermal conductivity of the new magnesium alloy is comparable to the A380 aluminium alloy. Commercially Alloy composition (wt. %)* Thermal conductivity (20°C, W/m·K) Al-9Si-3Cu-1Fe (A380) 110 Mg-9Al-1Zn-0.2Mn (AZ91D) 50 Mg-4Al-3.5Re-0.25Mn-0.2Zn (AE44) 82 Mg-3.5Al-4Re-0.3Mn-0.2Zn (AE44) 85 High thermal conductivity alloys composition (wt. %)* Thermal conductivity (20°C, W/m·K) Mg-5.5Re-0.2Zn-0.2Al-0.2Mn (BDM alloy) 110 Mg-5.1Re-0.1Y-0.3Zn-0.6Al-0.2Mn (BDM alloy) 107 Mg-4.8Re-0.1Y-0.2Zn-0.4Al-0.1Mn (BDM alloy) 105 Mg-5.5-0.1Y-0.2Zn-0.5Al-0.3Mn (BDM alloy) 108 * present in amounts of up to 20ppm Thermal conductivity is critical in applications specifically for increasing the capacity of heat exchange and heat sink of engineering components. Further details can be found in patent application WO2020221752.