Shahid R N, Scudino S
Institute for Complex Materials, IFW Dresden, Helmholtzstraße 20, D-01069, Dresden, Germany.
Sci Rep. 2018 Apr 24;8(1):6484. doi: 10.1038/s41598-018-24824-y.
Strengthening of alloys can be efficiently attained by the creation of harmonic structures: bimodal microstructures generated by controlled milling of the particulate precursors, which consist of coarse-grained cores embedded in a continuous fine-grained matrix. Here, we extend the concept of harmonic structures to metal matrix composites and analyze the effectiveness of such bimodal microstructures for strengthening composites consisting of a pure Al matrix reinforced with FeAl particles. Preferential microstructural refinement limited to the surface of the particles, where the FeAl phase is progressively fragmented, occurs during ball milling of the Al-FeAl composite powder mixtures. The refined surface becomes the continuous fine-grained matrix that encloses macro-regions with coarser reinforcing particles in the harmonic composites synthesized during subsequent powder consolidation. The generation of the bimodal microstructure has a significant influence on the strength of the harmonic composites, which exceeds that of the conventional material by a factor of 2 while retaining considerable plastic deformation. Finally, modeling of the mechanical properties indicates that the strength of the harmonic composites can be accurately described by taking into account both the volume fraction of reinforcement and the characteristic microstructural features describing the harmonic structure.
通过对颗粒前驱体进行可控研磨生成双峰微观结构，其由嵌入连续细晶粒基体中的粗晶粒核心组成。在此，我们将谐波结构的概念扩展到金属基复合材料，并分析这种双峰微观结构对强化由FeAl颗粒增强的纯Al基体复合材料的有效性。在Al-FeAl复合粉末混合物的球磨过程中，优先发生的微观结构细化仅限于颗粒表面，在该表面FeAl相逐渐破碎。在随后的粉末固结过程中合成的谐波复合材料中，细化的表面成为包围具有较粗增强颗粒的宏观区域的连续细晶粒基体。双峰微观结构的产生对谐波复合材料的强度有显著影响，其强度比传统材料高出2倍，同时仍保留相当大的塑性变形。最后，力学性能建模表明，通过考虑增强体的体积分数和描述谐波结构的特征微观结构特征，可以准确描述谐波复合材料的强度。
