Plastic flow behaviors of high-strength dual-phase Ni-SiOC nanocomposites
Plastic flow behaviors of high-strength dual-phase Ni-SiOC nanocomposites
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DOI：
10.1016/j.ijplas.2022.103431
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发表时间：
2022-09
影响因子：
9.8
通讯作者：
B. Wei;Wen-qing Wu;M. Nastasi;Lin Li;Jian Wang
中科院分区：
文献类型：
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作者：
B. Wei;Wen-qing Wu;M. Nastasi;Lin Li;Jian Wang
具有良好塑性流动稳定性的高强度材料对于结构应用来说是非常理想的。细化晶粒尺寸可以有效增强流动强度，但往往会导致塑性流动不稳定。在这里，我们证明了纳米级非晶陶瓷 SiOC 可以同时增强镍基纳米复合材料的强度和塑性流动稳定性。共溅射的 Ni-SiOC 纳米复合材料呈现出核（结晶 Ni）-壳（非晶态 SiOC）纳米结构，并在高达 800 °C 的退火过程中形成含有非晶态陶瓷 SiOC 纳米颗粒的纳米晶 Ni 复合材料。与所开发的微观结构相对应，在室温（RT）至400°C变形温度范围内的原位扫描电子显微镜（SEM）微柱压缩测试表明，核壳纳米结构在室温下表现出2.5 GPa的高强度，在400°C下表现出1.6 GPa的高强度，压缩应变高达40%，而含有非晶陶瓷纳米粒子的纳米晶镍复合材料在室温和400°C下表现出3.0 GPa的高强度。 400 °C 时为 2.0 GPa，压缩应变高达 50%。最有趣的是，两种纳米复合材料在压缩高达 50% 的过程中都没有表现出明显的应变硬化/软化行为。基于应变率跳跃测试测量的高应变率灵敏度（室温下为 0.02 至 400 °C 下为 0.05）和小激活体积（室温下为 8b3 至 400 °C 下为 10b3）表明位错滑移是镍晶粒中的主要变形机制，显微镜进一步证明了这一点。优异的塑性流动稳定性归因于微观结构促进非晶陶瓷和镍晶粒之间的塑性共同变形，微观结构表征证实了这一点。此外，非晶陶瓷SiOC抑制Ni晶粒粗化，防止变形引起的软化。
High-strength materials with good plastic flow stability are highly desirable for structural applications. Refining grain size can effectively enhance flow strength but often cause plastic flow instability. Here, we demonstrated that nanosized amorphous ceramics SiOC impart a simultaneous enhancement of strength and plastic flow stability to Ni-based nanocomposites. The co-sputtered Ni-SiOC nanocomposites exhibit core (crystalline Ni)-shell (amorphous SiOC) nanostructures and develop nanograined Ni composite containing amorphous ceramic SiOC nanoparticles during annealing up to 800 °C. Corresponding to the developed microstructures,in-situscanning electron microscope (SEM) micropillar compression tests at deformation temperatures range from room temperature (RT) to 400°C reveal that the core-shell nanostructure shows high strength of 2.5 GPa at RT and 1.6 GPa at 400 °C with compressive strain up to 40%, while the nanograined Ni composite containing amorphous ceramic nanoparticles exhibits high strength of 3.0 GPa at RT and 2.0 GPa at 400 °C with compressive strain up to 50%. Most intriguingly, both nanocomposites do not exhibit obvious strain hardening/softening behavior during compression up to 50%. The high strain rate sensitivity (0.02 at RT to 0.05 at 400 °C) and the small activation volume (8b3at RT to 10b3at 400 °C) that were measured based on strain rate jump tests suggest dislocation slips as dominant deformation mechanisms in Ni grains, which is further evidenced by microscopy. Superb plastic flow stability is attributed to microstructure-promoted plastic co-deformation between amorphous ceramics and Ni grains as confirmed by microstructure characterizations. Moreover, amorphous ceramic SiOC inhibit grain coarsening of Ni, preventing deformation induced softening.