Abstract Novel nanocomposites based on an AZ91 magnesium alloy matrix reinforced with a hybrid mixture of SiC and TiC nanoparticles with different nanoparticle contents (0.5% and 1%, by mass fraction) were fabricated by semi-solid stirring followed by ultrasonic vibration. Microstructural analysis indicated that the hybrid nanoparticles were uniformly distributed in the nanocomposite. The morphology of the Mg17Al12-based eutectic phase changed from plate-like, in the as-cast AZ91 alloy, to lamellar in the as-cast nanocomposites. The tensile strength and micro-hardness of the nanocomposites were improved by increasing the fraction of nanoparticles in the composite. Following extrusion, the matrix grains in the nanocomposite were significantly refined. The extent of the grain refinement increased at higher mass fractions of the nanoparticle. This refinement was not only due to dynamic recrystallization, but also the synergistic pinning effects arising from both the externally added nanoparticles as well as dynamically precipitated Mg17Al12 particles. The nanoparticle additions led to increases in yield strength (YS), ultimate tensile strength (UTS) and elongation to failure (EL). The increase in YS was mostly attributed to the effects of grain refinement, with additional contributions from the influence of Orowan strengthening and thermal expansion effects. The values of both the work hardening rate (θ) and strain hardening exponent (n) increased with increasing fraction of nanoparticles. The high θ value in stage III was attributed to both grain refinement and weakening of the basal plane texture, while the high n value was mainly related to the increase in resistance to dislocation movement caused by pinning effects of the nanoparticles.

中文翻译：

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杂化（SiC+TiC）纳米颗粒和动态沉淀物在高强度镁基纳米复合材料设计中的协同作用

摘要 通过半固态搅拌和超声振动制备了基于 AZ91 镁合金基体的新型纳米复合材料，该复合材料由具有不同纳米颗粒含量（0.5% 和 1%，按质量分数）的 SiC 和 TiC 纳米颗粒的混合混合物增强。微观结构分析表明混合纳米粒子均匀分布在纳米复合材料中。Mg17Al12 基共晶相的形态从铸态 AZ91 合金中的板状转变为铸态纳米复合材料中的层状。纳米复合材料的拉伸强度和显微硬度通过增加复合材料中纳米颗粒的比例得到改善。挤出后，纳米复合材料中的基体晶粒显着细化。晶粒细化的程度在纳米颗粒的质量分数较高时增加。这种细化不仅是由于动态再结晶，而且是由于外部添加的纳米粒子以及动态沉淀的 Mg17Al12 粒子产生的协同钉扎效应。添加纳米颗粒导致屈服强度 (YS)、极限拉伸强度 (UTS) 和断裂伸长率 (EL) 增加。YS 的增加主要归因于晶粒细化的影响，另外还有 Orowan 强化和热膨胀效应的影响。加工硬化率 (θ) 和应变硬化指数 (n) 的值都随着纳米颗粒比例的增加而增加。第三阶段的高 θ 值归因于晶粒细化和基面织构的减弱，