Enhancing specific energy absorption of additively manufactured titanium lattice structures through simultaneous manipulation of architecture and constituent material
Enhancing specific energy absorption of additively manufactured titanium lattice structures through simultaneous manipulation of architecture and constituent material
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DOI：
10.1016/j.addma.2022.102887
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发表时间：
2022-05-16
影响因子：
11
通讯作者：
Zhang, Ming-Xing
中科院分区：
文献类型：
--
作者：
Zhang, Jingqi;Liu, Yingang;Zhang, Ming-Xing
钛晶格结构已经发现了广泛的轻量化应用。然而，由常用的商业纯钛（CP-Ti）和Ti-6Al- 4V制成的晶格结构在单轴压缩下表现出低强度或屈服后软化/塌陷，使得它们对能量吸收应用不太有吸引力。在目前的工作中，一系列的钛gyroid晶格结构已被设计和增材制造的激光粉末床融合（L-PBF），以提高比能量吸收（SEA）通过操纵的架构和组成材料。实验结果表明，通过改变螺旋网格结构的板厚梯度，可以使网格结构中常见的先硬化后软化的宏观变形模式转变为连续硬化。向CP-Ti原料中添加MgO纳米颗粒通过氧溶质强化进一步提高了屈服强度，同时保持连续硬化行为而没有任何屈服后软化或塌陷。因此，当引入板厚度梯度和MgO时，由于连续硬化行为和高强度的组合，均匀的螺旋晶格结构的SEA提高了约63%。有限元分析的基础上修改体积硬化模型已经进行了揭示的基本机制，管理连续硬化行为。这项研究表明，巨大的潜力，结合建筑工程与材料设计，创造高性能的轻质网格结构的L-PBF。
Titanium lattice structures have found a wide range of lightweight applications. However, lattice structures made from the commonly-used commercially pure titanium (CP-Ti) and Ti-6Al- 4V exhibit either low strength or post-yielding softening/collapse under uniaxial compression, making them less attractive to energy absorbing applications. In the present work, a series of titanium gyroid lattice structures have been designed and additively manufactured by laser powder bed fusion (L-PBF) to enhance the specific energy absorption (SEA) through manipulation of the architecture and the constituent material. Experimental results show that tailoring the sheet thickness gradient of gyroid lattice structures enables the transformation of the macroscopic deformation mode from hardening followed by softening, which is commonly seen in lattice structures, to continuous hardening. The addition of MgO nanoparticles to CP-Ti feedstock further improves the yield strength through oxygen solute strengthening, while maintaining the continuous hardening behaviour without any post-yielding softening or collapse. As a result, when both sheet thickness gradient and MgO are introduced, the SEA of the uniform gyroid lattice structure is enhanced by approximately 63% due to the combination of continuous hardening behaviour and high strength. Finite element analysis based on the modified volumetric hardening model has been performed to shed light on the underlying mechanism that governs the continuous hardening behaviour. This study demonstrates the tremendous potential of marrying architecture engineering with material design to create high performance lightweight lattice structures by L-PBF.