Microstructure and mechanical properties of 3D ink-extruded CoCrCuFeNi microlattices
Microstructure and mechanical properties of 3D ink-extruded CoCrCuFeNi microlattices
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DOI：
10.1016/j.actamat.2022.118187
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发表时间：
2022-07
期刊：
影响因子：
9.4
通讯作者：
Dingchang Zhang;C. Kenel;D. Dunand
中科院分区：
文献类型：
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作者：
Dingchang Zhang;C. Kenel;D. Dunand
具有正交0-90°结构的微晶格是由含有氧化物粉末（Co3O4, CuO， Fe2O3和NiO）和金属粉末（Cr）的混合物的油墨3d挤出打印的。然后通过h2还原氧化物，然后烧结和金属的相互扩散，合成了直径为~ 170µm的等原子CoCrCuFeNi微晶格。这些工艺步骤通过原位同步加速器x射线衍射在直径为~ 250µm的单挤压微丝（晶格杆）上进行了研究。在600℃和H2条件下，经过1 h的还原和部分互扩散后，细丝由轻度烧结的金属颗粒和部分未还原的Cr2O3组成。在1050˚C和H2条件下，经过4 h的固相均质处理，得到了一种还原的、几乎完全致密化（孔隙率：1.6±0.7%）的合金，其显微组织由两个面心立方相组成，一个贫cu，另一个富cu。在1050℃的均质化过程中，在1150℃下加热10 min，形成富cu熔体，增强致密性（孔隙率：0.3±0.2%），并使柱状表面和微晶格节点处的尖尖变得光滑。液体烧结微晶格比固体烧结微晶格具有更高的抗压强度和延展性。这些改进与有限元模拟结果一致，表明凝固的熔体平滑了节点处的尖峰，降低了应力集中。这些CoCrCuFeNi微晶格可以集成到更复杂的承重应用中，例如，作为具有不同寻常的高比刚度、强度和韧性组合的夹层结构的核心。
Microlattices with orthogonal 0-90° architecture are 3D-extrusion printed from inks containing a blend of oxide powders (Co3O4, CuO, Fe2O3, and NiO) and metal powder (Cr). Equiatomic CoCrCuFeNi microlattices with ∼170 µm diameter struts are then synthesized by H2-reduction of the oxides followed by sintering and interdiffusion of the resulting metals. These process steps are studied byin-situsynchrotron X-ray diffraction on single extruded microfilaments (lattice struts) with ∼250 µm diameter. After reduction and partial interdiffusion at 600 ˚C for 1 h under H2, filaments consist of lightly-sintered metallic particles with some unreduced Cr2O3. A reduced, nearly fully densified (porosity: 1.6 ± 0.7%) alloy is obtained after solid-state homogenization at 1050 ˚C for 4 h under H2, with a microstructure consisting of two face-centered-cubic phases, one Cu-poor and the other Cu-rich. When a 10 min excursion to 1150 ˚C is added to the 1050 ˚C homogenization, a Cu-rich melt forms which enhances densification (porosity: 0.3 ± 0.2%) and smooths both strut surfaces and sharp cusps at nodes in the microlattices. The liquid-sintered microlattices show higher compressive strength and ductility than the solid-sintered microlattices. These improvements are consistent with finite-element modeling results which show that smoothening of the sharp cusps at nodes by the solidified melt reduces stress concentrations. These CoCrCuFeNi microlattices can be integrated in more complex load-bearing applications, e.g., as cores of sandwich structures with an unusual combination of high specific stiffness, strength, and toughness.