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，镁合金在轻量化结构应用方面的兴趣在过去十年中稳步增长。但镁合金有限的强度和延展性是目前镁合金研究的一大难题。然而，最近，纳米级增强剂的使用已经导致镁合金性能的显著改善。纳米颗粒在镁基金属基纳米复合材料中的均匀分布是制备镁基金属基纳米复合材料所面临的巨大挑战，而纳米颗粒的团聚和聚类又加剧了这一挑战。本项目的主要目的是合成完全致密的镁纳米结构，该结构由均匀分布的SiC纳米颗粒增强。计划通过机械铣削和适当的固结工艺，合成具有高体积分数（高达10体积%）增强的纳米复合材料，并将镁基体的晶粒尺寸减小到纳米级。本研究旨在探讨在准静态和循环加载速率下，SiC纳米颗粒对Mg-SiC纳米复合材料力学性能的潜在机制和影响。微观结构分析支持的力学测试为评估镁纳米复合材料中不同强化机制的效果提供了数据。该项目的研究成果可用于提高镁纳米复合材料的制造能力，使其具有高体积分数和均匀分布的纳米颗粒，从而改善其力学性能。在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.