Scifacturing Laboratory, Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095, USA.
Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA.
Nature. 2015 Dec 24;528(7583):539-43. doi: 10.1038/nature16445.
Magnesium is a light metal, with a density two-thirds that of aluminium, is abundant on Earth and is biocompatible; it thus has the potential to improve energy efficiency and system performance in aerospace, automobile, defence, mobile electronics and biomedical applications. However, conventional synthesis and processing methods (alloying and thermomechanical processing) have reached certain limits in further improving the properties of magnesium and other metals. Ceramic particles have been introduced into metal matrices to improve the strength of the metals, but unfortunately, ceramic microparticles severely degrade the plasticity and machinability of metals, and nanoparticles, although they have the potential to improve strength while maintaining or even improving the plasticity of metals, are difficult to disperse uniformly in metal matrices. Here we show that a dense uniform dispersion of silicon carbide nanoparticles (14 per cent by volume) in magnesium can be achieved through a nanoparticle self-stabilization mechanism in molten metal. An enhancement of strength, stiffness, plasticity and high-temperature stability is simultaneously achieved, delivering a higher specific yield strength and higher specific modulus than almost all structural metals.
镁是一种轻金属，密度为铝的三分之二，在地球上储量丰富，而且具有生物兼容性；因此，它有可能提高航空航天、汽车、国防、移动电子和生物医学应用领域的能源效率和系统性能。然而，传统的合成和加工方法（合金化和热机械加工）在进一步提高镁和其他金属的性能方面已经达到了一定的极限。陶瓷颗粒已被引入金属基体中以提高金属的强度，但不幸的是，陶瓷微球严重降低了金属的塑性和可加工性，而纳米颗粒虽然具有在保持甚至提高金属塑性的同时提高强度的潜力，但在金属基体中难以均匀分散。在这里，我们通过熔融金属中的纳米颗粒自稳定机制证明，在镁中可以实现碳化硅纳米颗粒（体积分数为 14%）的致密均匀分散。同时实现了强度、刚度、塑性和高温稳定性的提高，比几乎所有结构金属都具有更高的比屈服强度和比弹性模量。
