Simultaneous enhancement of powder properties, additive manufacturability, and mechanical performance of Ti-6Al-4V alloy by 2D-nanocarbon decoration
Simultaneous enhancement of powder properties, additive manufacturability, and mechanical performance of Ti-6Al-4V alloy by 2D-nanocarbon decoration
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DOI：
10.1016/j.msea.2022.144215
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发表时间：
2022-10-26
期刊：
影响因子：
6.4
通讯作者：
Nomura, Naoyuki
中科院分区：
文献类型：
--
作者：
Dong, Mingqi;Zhou, Weiwei;Nomura, Naoyuki
对复合粉末性能的认识不足是设计高性能激光粉床熔化金属零件的瓶颈。众所周知，传统的颗粒状或纤维状填充剂会导致粉末流动性降低，并导致复合粉末的形貌无法控制。在这项工作中，我们展示了第一个例子，以改善粉末性质和L-PBF的金属粉末装饰二维(2D)纳米薄膜的可制造性。采用静电自组装的方法在Ti-6Al-4V(Ti64)粉末表面均匀地附着了0.5wt%的氧化石墨烯(GO)，其球状形貌和颗粒大小不受影响。GO修饰的Ti64(GO@Ti64)粉床的质量显著提高，由一种新的离心分离测试和再涂覆实验的结果表明，这归因于粉末/粉末和粉末/基材粘附力的显著降低。此外，虽然GO@Ti64粉末的导热系数降低，但由于GO的多个局部吸收，导致激光吸收率增加。因此，GO@Ti64粉末的最佳加工区被延长并变得更宽，增强了L-PBF的印刷适宜性。高分辨电子显微镜观察表明，GO/Ti64组织完全由板条宽度接近91 nm的超细马氏体相组成。这种新的结构归因于L-PbF的高温、非平衡致密化；2D GO纳米片在Ti64基质中的完全溶解产生了一种新的碳过饱和、无沉淀的结构。晶粒细化和固溶强化使GO/Ti64合金的屈服强度从1375 Mpa提高到1793 Mpa，抗压强度从1796 Mpa提高到2032 Mpa。这一研究结果有助于更好地了解复合粉末的性能，并可被视为朝着通过L-PBF制备高性能金属部件迈出的重要一步。
Poor understanding of composite powder properties is a bottleneck in the design of high-performance metallic components via laser powder bed fusion (L-PBF). Traditional particle- or fiber-like fillers are known to result in reduced powder flowability and the uncontrollable morphology of composite powders. In this work, we demonstrate a first example of improving the powder properties and L-PBF manufacturability of metallic powders decorated by two-dimensional (2D) nanofillers. 0.5 wt% graphene oxide (GO) sheets were uniformly adhered onto the surface of Ti-6Al-4V (Ti64) powders via an electrostatic self-assembly, with their spherical morphology and particle size uncompromised. The notably enhanced quality of the GO-decorated Ti64 (GO@Ti64) powder bed, indicated by the results of a novel centrifugal separation testing and a recoating experiment, was attributed to the significant reduction in powder/powder and powder/substrate adhesive forces. Moreover, while the thermal conductivity of the GO@Ti64 powders was found to decrease, the laser absorptivity increased as a result of multiple local absorptions of wrinkled GO. The optimal process zone of GO@Ti64 powders was therefore shown to have been extended and to have become wider, enhancing L-PBF printability. High-resolution transmission electron microscopy inspections revealed that the GO/Ti64 build fully consisted of ultrafine martensite structures with a lath width of similar to 91 nm. This novel structure was attributed to the high-temperature, nonequilibrium densification of L-PBF; the complete dissolution of the 2D GO nanosheets into the Ti64 matrix generated a novel carbon-supersaturated, precipitation-free structure. The grain refinement and solid-solution strengthening behaviors led to an increase in the yield strength of the GO/Ti64 build from 1375 MPa to 1793 MPa, and also an increase in its compressive strength, from 1796 MPa to 2032 MPa. The results of this investigation contribute to a better understanding of composite powder properties and can be seen as a significant step toward the preparation of high-performance metallic components via L-PBF.