Abstract A nanocrystalline surface layer with average grain size of 98 nm of Mg-6Zn-0.2Y-0.4Ce-0.5Zr (wt%) alloy was fabricated successfully by sliding friction treatment (SFT). The abundant second-phase particles are heavily broken and homogeneously distributed in the matrix after SFT. Electron backscattered diffraction (EBSD) indicates that the intensity of basal texture shows a gradually decreasing trend with the decreasing distance from the treated surface due to the new recrystallized grains with random grain orientation. The process of grain refinement is found to involve the following stages: (i) the twins and dislocations are activated under the low strain area; (ii) the high density of dislocations accumulated near the second-phase particles promote the formation of substructures and the shear bands; (iii) the increasing strain arouses the transformation of substructures; (iv) multiple stacking faults will induce the nucleation of new strain-free grains under the high strain; (v) the nanosized grains are acquired. The abundant fine second-phase particles give large contribution for the refining process due to the pinning effect on the dislocations.

中文翻译：

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滑动摩擦处理的Mg-Zn-Y-Ce-Zr合金超细晶粒表层组织演变

摘要 Mg-6Zn-0.2Y-0.4Ce-0.5Zr (wt%)合金通过滑动摩擦处理(SFT)成功制备了平均晶粒尺寸为98 nm的纳米晶表面层。大量的第二相颗粒在 SFT 后严重破碎并均匀分布在基体中。电子背散射衍射（EBSD）表明，由于新的再结晶晶粒具有随机晶粒取向，基底织构的强度随着距处理表面距离的减小而呈现逐渐减小的趋势。发现晶粒细化过程涉及以下阶段：(i)孪晶和位错在低应变区下被激活；(ii) 在第二相粒子附近积累的高密度位错促进了亚结构和剪切带的形成；(iii) 增加的应变引起子结构的转变；(iv) 多个堆垛层错将在高应变下诱导新的无应变晶粒的形核；(v) 获得纳米尺寸的晶粒。由于位错的钉扎效应，丰富的细小第二相颗粒对精炼过程有很大贡献。