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

由于其低密度和高比性能，镁（Mg）合金用于轻质结构应用的兴趣在过去十年中稳步增长。但镁合金的强度和塑性有限是目前镁合金面临的一大挑战。然而，最近，纳米尺寸的增强体的使用已经导致镁合金的性能的显著改善。纳米颗粒在镁结构中的均匀分散是镁基金属基纳米复合材料制备的一个巨大挑战，而纳米颗粒的团聚和聚集又加剧了这一挑战。该项目的主要目的是合成完全致密的镁纳米结构，其由均匀分布的SiC纳米颗粒增强。计划合成具有高体积分数的增强材料的纳米复合材料，高达10体积%，并通过机械研磨和适当的固结工艺将镁基体的晶粒尺寸减小到纳米范围。本研究旨在研究和讨论潜在的机制和SiC纳米颗粒对Mg-SiC纳米复合材料在准静态和循环加载速率下的力学性能的影响。由微观结构分析支持的机械测试提供数据来评估在镁纳米复合材料中起作用的不同强化机制的效果。该项目的成果可用于提高镁纳米复合材料的制造能力，具有高体积分数和均匀分布的纳米颗粒，随后导致机械性能的改善。与纳米复合材料的合成、表征、准静态和循环性能有关的科学知识和工程开发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.