Processing, microstructure evolution and mechanical properties (under quasi-static and cyclic loading) of Mg-SiC nanocomposites

由于镁合金的低密度和高比性能，在过去的十年里，人们对用于轻量化结构应用的镁合金的兴趣稳步增加。但镁合金的强度和塑性有限是目前面临的一大挑战。然而，最近，纳米增强材料的使用使镁合金的性能有了显著的改善。纳米颗粒在镁结构中的均匀分散对镁基金属基纳米复合材料的制备是一个巨大的挑战，而纳米颗粒的团聚和聚集加剧了这一挑战。本项目的主要目标是合成完全致密的纳米镁结构，并通过均匀分布的纳米碳化硅颗粒对其进行增强。计划通过机械球磨和适当的固结工艺，合成高体积分数的增强体，高达10vol.%的纳米复合材料，并将镁基体的颗粒尺寸减小到纳米级。本研究旨在研究和探讨纳米碳化硅颗粒在准静态和循环加载速率下对镁-碳化硅纳米复合材料力学性能的影响及其机理。微观结构分析支持的力学测试为评价镁纳米复合材料中不同强化机制的效果提供了数据。项目成果可用于提高具有高体积分数和纳米颗粒均匀分布的镁纳米复合材料的制造能力，从而改善力学性能。有关纳米复合材料的合成、表征、准静态和循环性能方面的科学知识和工程发展也是该项目的成果之一。

Due to their low density and high specific properties, the interest in magnesium (Mg) alloys for lightweight structural applications has steadily increased over the last decade. But limited strength and ductility of Mg alloys is a big challenge up to now. Recently, however, the use of nano-sized reinforcements has resulted in appreciable improvements in the performance of Mg alloys. Dispersing of nanoparticles uniformly in magnesium structure is a huge challenge for processing of Mg-based metal matrix nanocomposites, and exacerbated by the agglomeration and clustering of nanoparticles. The primary aim of this project is to synthesize fully dense magnesium nanostructured which are reinforced with a uniform distribution of SiC nanoparticles. It is planned to synthesize nanocomposites with a high volume fraction of the reinforcement, up to 10 vol.%, and reduced grain sizes of the magnesium matrix to nano-regime, by mechanical milling and proper consolidation processes. The present study aimed to investigate and discuss the underlying mechanisms and effect of SiC nanoparticles on the mechanical properties of the Mg-SiC nanocomposites under quasi-static and cyclic loading rates. The mechanical tests supported by microstructural analysis provide data to evaluate the effects of different strengthening mechanisms that are operative in the magnesium nanocomposites. The project outcome could be employed to enhance the manufacturing capabilities of magnesium nanocomposites with high volume fraction and uniform distribution of nanoparticles which subsequently lead to improvement in mechanical properties. The scientific knowledge and the engineering developments relating to nanocomposite materials in terms of synthesis, characterization, quasi-static and cyclic properties are also among the achievements of this project.