发表机构
University of Michigan – Ann Arbor（密歇根大学安娜堡分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究通过激光快速凝固制备Al-(Si,Ge)共晶，利用界面约束和硬相化学耦合机制促进金属与共价相协同变形，实现高强度与高延展性兼得。
AI 中文摘要
共晶提供了一条通过将微观结构细化与相特定的化学和晶体学层级结构相结合，来克服异质相异质结构中塑性不相容性的途径。在此，我们研究了沿单变三元共晶路径设计的激光快速凝固Al-(Si,Ge)共晶复合材料，其凝固形成富铝面心立方(fcc)基体和富(Si,Ge)金刚石立方(dc)纤维作为组成共晶相，并具有小面化界面。微观结构本质上是分层的，共晶相内具有更精细的结构：Al相中的纳米尺度(Si,Ge)团簇以及(Si,Ge)纤维内的生长孪晶，且伴有少量Al残留。尽管增加Ge含量会使共晶间距粗化，但与相对更细的Al-Si相比，屈服强度略有提高，且Al-(Si,Ge)的拉伸延展性高于Al-Si。原位SEM微力学测试结合事后STEM和TEM表明，在富Al相中，Ge偏析到变形诱导的亚晶界上，这些亚晶界限制了滑移位错。同时，富(Si,Ge)纤维在大塑性应变下仍保持抗裂纹能力，并表现出变形诱导的平面缺陷，这与高应力界面和孪晶边界处的局部部分位错活动一致。这些由界面约束和硬相化学引起的耦合机制使金属相和共价相能够协同变形，为设计超越传统长度尺度控制强化的高抗拉强度和延展性分层共晶提供了途径。
英文摘要
Eutectics offer a route to overcome plastic incompatibility in disparate-phase heterostructures by coupling microstructural refinement with phase-specific chemical and crystallographic hierarchy. Here, we investigate laser-rapid-solidified Al-(Si,Ge) eutectic composites designed along the univariant ternary eutectic path, solidifying with an Al-rich face-centered cubic (fcc) matrix and (Si,Ge)-rich diamond-cubic (dc) fibers as constituent eutectic phases with faceted interfaces. The microstructure was hierarchical in nature with finer structures within eutectic phases: nanoscale (Si,Ge) clusters in the Al phase and growth twins within the (Si,Ge) fibers with some Al retention. Although increasing Ge content coarsens the eutectic spacing, the yield strength is slightly enhanced compared to the relatively finer Al-Si, and tensile ductility of Al-(Si,Ge) is higher than that of Al-Si. In situ SEM micromechanical testing combined with post-mortem STEM and TEM showed that in the Al-rich phase, Ge segregated to the deformation-induced sub-grain boundaries that confined glide dislocations. Simultaneously, the (Si,Ge)-rich fibers remain crack-resistant at large plastic strain and exhibit deformation-induced planar faults, consistent with localized partial-dislocation activity at highly stressed interfaces and twin boundaries. These coupled mechanisms due to interface confinement and hard phase chemistry enable co-deformation of the metallic and covalent phases, providing a pathway for designing high-tensile-strength and ductile hierarchical eutectics beyond conventional length-scale-controlled strengthening.
