Carbon Nanotubes Enabled Laser 3D Printing of High-Performance Titanium with Highly Concentrated Reinforcement

Abstract

Summary Zero- to two-dimensional nanomaterials have been incorporated into metal-matrices to improve the strength of metals, but challengingly, high-volume-fraction nanomaterials are difficult to disperse uniformly in metal matrices, severely degrading the ductility of conventionally processed metals. Here, a considerably dense uniform dispersion of in situ formed nanoscale lamellar TiC reinforcement (16.1 wt %) in Ti matrix is achieved through laser-tailored 3D printing and complete reaction of Ti powder with a small amount (1.0 wt %) of carbon nanotubes (CNTs). An enhanced tensile strength of 912 MPa and an outstanding fracture elongation of 16% are simultaneously achieved for laser-printed components, showing a maximum 350% improvement in “product of strength and elongation” compared with conventional Ti. In situ nanoscale TiC reinforcement favors the formation of ultrafine equiaxed Ti grains and metallurgically coherent interface with minimal lattice misfit between TiC lamellae and Ti matrix. Our approach hopefully provides a feasible way to broaden structural applications of CNTs in load-bearing Ti-based engineering components via laser-tailored reorganization with Ti.

Effects of Laser Energy Density on Carbon‐Nanotube‐Reinforced Titanium Composites Printed via Selective Laser Melting

“…Postetching analysis in the SEM reveals what appear to be carbide formations on the surface, which are not observed in the control Ti64 samples. Their small scale (%500 nm) prevented their direct identification by EDS analysis, but the visual observation aligns with those of Gu et al [13] Figure 7 shows a progression of this carbide formation as observed in SEM. In Figure 7a an intact CNT is observed moving in and out of plane of the observable surface-identified by its dimensions and charging of electrons.…”

“…In Figure 7a an intact CNT is observed moving in and out of plane of the observable surface-identified by its dimensions and charging of electrons. It is noteworthy that this appears to be the first study on the SLM of Ti-CNT where some CNTs survive into the final printed structure; this is attributed to the lower laser energy density used as compared to previous studies [13,14,29] and the relatively high purity (>95 wt%) of CNTs used in the current study. Figure 7b then shows a linear chain of carbides with similar morphology to the nanotubes used in this study, representing a CNT that has entirely reacted to TiC x .…”

“…However, the composite samples show two additional, unidentified peaks of lower intensity, which can be observed at 2θ % 36.25 and 42.25 . Gu et al [13] showed that for SLMproduced Ti-CNT composites, peaks can occur in this vicinity, which are associated with substoichiometric titanium carbides (TiC x ). The primary peaks for TiC occur at 2θ % 36 and 42 (ICDD PDF# 01-089-3828).…”

“…Although most studies producing Ti-CNT composites have focused on spark plasma sintering and/or hot pressing, [9][10][11][12] a few studies have been done that explore 3D printing to manufacture them. Gu et al [13] utilized low-energy ball milling to create a homogeneous, composite powder of commercially pure Ti and 1 wt% CNTs. The resultant powder was printed using SLM, yielding a composite with a 350% increase in the product of strength and elongation (a measure of toughness.)…”

Novel silicon bipodal cylinders with controlled resonances and their use as beam steering metasurfaces

“…It has been shown that it is possible to etch silicon nanotubes with very specific dimensions using oxygen plasma etching 33 . Moreover, Chen et al were able to fabricate mutipodal Silicon Nanotubes via Anodic Aluminum Oxide template-assisted Approach 34 . Not to mention that with the use of additive manufacturing and with the presence of rapidly growing technologies like nano-scale 3D printing 35 , the fabrication of BPCs seems very feasible.…”