A surface composite layer enhances the mechanical characteristics of a surface while retaining the properties of the base material. Friction stir processing (FSP) is a method for forming surface metal matrix composites (SMMCs) that reinforce a surface with particles. In the current study, a new method entitled friction stir vibration processing (FSVP) was applied to form SMMCs on the surface of AZ91 magnesium alloy with SiC particles as the reinforcing particles. Contrary to FSP, in FSVP, the workpiece was vibrated normal to the processing line while the tool rotated and traversed. The microstructure and mechanical properties of friction stir (FS) and friction stir vibration (FSV) processed specimens were evaluated. Additionally, the effects of vibration frequency and process parameters on different characteristics of FS and FSV processed specimens were studied. The results showed that the stir zone grains for FSV processed specimens were finer than those for FS processed specimens, and the second phase particles (SiC particles) had a more homogenous distribution in the former specimens than in the latter specimens. This was related to the effect of workpiece vibration during FSVP, which increased the material deformation and led to enhanced dynamic recrystallization and the breakdown of agglomerated SiC particles. The results indicated that the stir zone grain size decreased, and the distribution homogeneity of the SiC particles increased as vibration frequency increased. It was also observed that the stir zone grain size increased, and the mechanical properties of the processed specimens decreased as tool rotation speed increased.

中文翻译：

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FSP开发AZ91 / SiC表面复合材料：振动和工艺参数对组织和力学性能的影响。

表面复合层增强了表面的机械特性，同时保留了基材的性能。搅拌摩擦加工（FSP）是一种形成表面金属基复合材料（SMMC）的方法，该复合材料用颗粒增强表面。在当前的研究中，一种名为摩擦搅拌振动处理（FSVP）的新方法被应用在以SiC颗粒为增强颗粒的AZ91镁合金表面上形成SMMC。与FSP相反，在FSVP中，当刀具旋转和移动时，工件垂直于加工线振动。评价了搅拌摩擦（FS）和搅拌摩擦振动（FSV）处理的试样的微观结构和力学性能。另外，研究了振动频率和工艺参数对FS和FSV加工试样不同特性的影响。结果表明，FSV加工样品的搅拌区晶粒比FS加工样品的搅拌区晶粒细，第二相颗粒（SiC颗粒）在前一个样品中的分布比后一个样品更均匀。这与FSVP期间工件振动的影响有关，后者增加了材料变形并导致增强的动态再结晶和团聚的SiC颗粒的破裂。结果表明，随着振动频率的增加，搅拌区晶粒尺寸减小，SiC颗粒的分布均匀性增加。还观察到搅拌区晶粒尺寸增加，