A novel structure-optimized SiC fiber reinforced metal-intermetallic-laminated composite (SiC_f-Ti/Al₃Ti) without intermetallic centerline defect has been fabricated by vacuum hot pressing using stacked fibers and foils as well as Ti barrier layer. Through microstructure characterization by SEM and EBSD, the mechanisms of centerline formation and structural optimization were investigated detailedly. The mechanical properties and fracture behaviors of the optimized and non-optimized SiC_f-Ti/Al₃Ti composites were studied via quasi-static compression tests. The experimental results indicated that the intermetallic centerline region existing at the mid-plane of Al₃Ti layer in non-optimized composite mainly contains newly-formed Kirkendall voids and gathered metallic oxides. Additionally, owing to the similar moving trails of fibers, oxides and voids in molten Al during hot pressing, SiC fiber is always accompanied with centerline, which causes the poor bonding of SiC_f/Al₃Ti interface. Unlike that, due to the adding of Ti barrier layer, SiC fibers are separated from centerline and metallurgically bonded with Al₃Ti intermetallic in the optimized composite. The compression testing results proved that the optimized SiC_f-Ti/Al₃Ti composite possesses superior strength and toughness compared with those of the non-optimized composite. Besides, the extending of cracks along centerline often leads to large-scale centerline splitting and untimely SiC_f/Al₃Ti interface debonding in non-optimized composite. Nevertheless, cracks formed in optimized composite tend to propagate at the interfacial zone between layers instead of cutting off Al₃Ti layer along its mid-plane. Moreover, ascribed to the well-bonded SiC_f/Al₃Ti interface, SiC fibers play an important role in strengthening and toughening the optimized SiC_f-Ti/Al₃Ti composite by fiber bridging mechanism.

Graphic Abstract

中文翻译：

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钛阻挡层合成SiC纤维增强Ti / Al 3 Ti层状复合材料的组织和力学性能优化机理

利用堆叠的纤维和箔以及钛阻挡层，通过真空热压法制备了一种新型的结构优化的SiC纤维增强金属-金属间层合复合材料（SiC _f -Ti / Al ₃ Ti）。通过SEM和EBSD的微观结构表征，详细研究了中心线形成的机理和结构优化。通过准静态压缩试验研究了优化的和未优化的SiC _f -Ti / Al ₃ Ti复合材料的力学性能和断裂行为。实验结果表明，存在于Al ₃中平面的金属间中心线区域未经优化的复合材料中的钛层主要包含新形成的柯肯达尔孔隙和聚集的金属氧化物。另外，由于热压过程中熔融铝中纤维，氧化物和空隙的运动轨迹相似，SiC纤维始终伴随中心线，这导致SiC _f / Al ₃ Ti界面的粘结性较差。与此不同的是，由于添加了Ti阻挡层，因此在优化的复合材料中，SiC纤维从中心线分离并与Al ₃ Ti金属间化合物冶金结合。压缩测试结果表明，优化的SiC _f -Ti / Al ₃与未优化的复合材料相比，Ti复合材料具有优异的强度和韧性。此外，裂纹沿着中心线的扩展通常会导致大规模的中心线分裂，并且在未优化的复合材料中导致SiC _f / Al ₃ Ti界面不及时脱胶。然而，在优化的复合材料中形成的裂纹倾向于在各层之间的界面区域传播，而不是沿其中间平面切断Al ₃ Ti层。此外，归因于良好结合的SiC _f / Al ₃ Ti界面，SiC纤维在通过纤维桥接机制增强和增韧优化的SiC _f -Ti / Al ₃ Ti复合材料中起着重要作用。

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