Improving the Young's modulus of Mg via alloying and compositing – A short review

Lightweight, high-modulus structural materials are highly desired in many applications like aerospace, automobile and biomedical instruments. As the lightest metallic structural material, magnesium (Mg) has great potential but is limited by its low intrinsic Young's modulus. This paper reviews the investigations on high-modulus Mg-based materials during the last decades. The nature of elastic modulus is introduced, and typical high-modulus Mg alloys and Mg matrix composites are reviewed. Specifically, Mg alloys enhance Young's modulus of pure Mg mainly by introducing suitable alloying elements to promote the precipitation of high-modulus second phases in the alloy system. Differently, Mg matrix composites improve Young's modulus by incorporating high-modulus particles, whiskers and fibers into the Mg matrix. The modulus strengthening effectiveness brought by the two approaches is compared, and Mg matrix composites stand out as a more promising solution. In addition, two well-accepted modulus prediction models (Halpin-Tsai and Rule of mixtures (ROM)) for different Mg matrix composites are reviewed. The effects of reinforcement type, size, volume fraction and interfacial bonding condition on the modulus of Mg matrix composites are discussed. Finally, the existing challenges and development trends of high-modulus Mg-based materials are proposed and prospected.