Study on the junction zone of NiTi shape memory alloy produced by selective laser melting via a stripe scanning strategy

Guo, Wenqian; Yang, Ying; Wang, Xiebin; Xiong, Zhiwei; Li, Zhonghan; Wang, Cheng; Cui, Lishan; Huang, Shuke; Li, Meng; Hao, Shijie

doi:10.1016/j.intermet.2020.106947

Cited by 21 publications

(11 citation statements)

References 44 publications

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Section: Resultsmentioning

confidence: 99%

“…[34] Second, the alternating distribution of large and small melt pools caused by the starting and ending of the laser could disturb the crystallographic orientation inheritance and weaken the texture. [35] Differences in the microstructure caused by different scanning strategies could lead to anisotropic mechanical behavior of LPBF-printed parts. As stronger microstructure along the building direction was found in XY-scan samples than in Y-scan samples, the degree of anisotropic mechanical behavior could be higher in XY-scan samples than in Y-scan samples, which is attributed to the different cracking mechanisms.…”

Section: Morphology and Microstructurementioning

confidence: 99%

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Effect of Scanning Strategies on the Microstructure and Mechanical Properties of Inconel 718 Alloy Fabricated by Laser Powder Bed Fusion

et al. 2022

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The scanning strategy is an essential factor that determines the thermal history and combination of melt tracks within parts in the laser powder bed fusion (LPBF) process, which can significantly influence the microstructure evolution, defect formation, and mechanical properties of parts. Herein, the effect of scanning strategies (i.e., Y‐scan, XY‐scan, Rot‐scan, and Island‐scan) on the microstructure and mechanical properties of Inconel 718 (IN718) parts manufactured by LPBF is investigated. The results show that different scanning strategies can lead to different morphologies of melt tracks, and the Rot‐scan is the most beneficial strategy for improving density of parts. Different scanning strategies change the direction of the temperature gradient within parts, resulting in different morphologies of grain growth. The tensile properties of samples built with four types of scanning strategies show superior mechanical properties compared with the cast. The ultimate tensile strength of samples manufactured by Y‐scan, XY‐scan, and Rot‐scan is equivalent to that of the wrought, while the ductility of them is higher than that of wrought. However, tensile properties of samples manufactured by island scanning are lowest due to defects (e.g., pores, spatters) at the overlap of islands.

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Section: Resultsmentioning

confidence: 99%

Section: Morphology and Microstructurementioning

confidence: 99%

Effect of Scanning Strategies on the Microstructure and Mechanical Properties of Inconel 718 Alloy Fabricated by Laser Powder Bed Fusion

et al. 2022

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“…Materials based on TiNi alloys fabricated via more conventional methods such as powder metallurgy [15,16] (including, hot-press sintering [17], spark plasma sintering (SPS) [18][19][20], etc. ), can be further modified using ion-plasma [21,22], ion-beam [23,24], laser-beam [25][26][27] or other similar treatments.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Electron-Beam Surface Modification of Novel TiNi Material for Medical Applications

et al. 2021

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A new approach to fabricate TiNi surfaces combining the advantages of both monolithic and porous materials for implants is used in this work. New materials were obtained by depositing a porous TiNi powder onto monolithic TiNi plates followed by sintering at 1200 °C. Then, further modification of the material surface with a high-current-pulsed electron beam (HCPEB) was carried out. Three materials obtained (one after sintering and two after subsequent beam treatment by 30 pulses with different pulse energy) were studied by XRD, SEM, EDX, surface profilometry, and by means of electrochemical measurements, including OCP and EIS. Structural and compositional changes caused by HCPEB treatment were investigated. Surface properties of the samples during their storage in saline for 10 days were studied and a model experiment with cell growth (MCF-7) was carried out for the unmodified sample with an electron beam to detect cell appearance on different surface locations.

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“…and, more recently additive manufacturing processes that include, for example, selective laser sintering (SLS), selective laser melting (SLM) and laser engineered net shaping (LENS) (Ref 6). In the scope of additive manufacturing, recent works (Ref [10][11][12][13][14] have applied and evaluated the effects of different processing techniques to produce NiTi alloys.…”

Section: Introductionmentioning

confidence: 99%

Production of Cylindrical Specimens Based on the Ni-Ti System by Selective Laser Melting from Elementary Powders

Oliveira

Lima

Sallet

et al. 2021

J. of Materi Eng and Perform

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This study aimed to evaluate the potential use of elemental powders, Ni oxyreduction and Ti HDH (hydration-dehydration) to obtain the NiTi shape memory alloy in cylindrical specimens from additive manufacturing process by Selective Laser Melting with laser power and energy density under control (100 to 150 W and 25 to 40 J/mm 3 ). Scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) conjugated analyses showed that all processing parameters yield samples with Ti enriched regions surrounded by alloy layers associated to Ni 3 Ti, Ni 3 Ti 2 , and NiTi 2 intermetallic. This evidence suggests that the parameters applied were not enough to promote the complete fusion of Ti particles, indicating that the samples presented a melting microstructure with evidence of defects located due to lack of fusion due to the irregular voids and Ti islands that resemble the irregular morphology of the starting Ti HDH powder, and pores depending on the retention of gases in the fusion pool. Each explored condition presented in its structure a set of different phases in nature and proportion, without the NiTi intermetallic. Also, justifies the apparent and real density values not compatible with the NiTi intermetallic theoretical density, but the density resulting from the mixture of different Ni-Ti system phases formed. Observing the decrease in the cracks and pores, and the real densities measured, compared with the theoretical density of the NiTi intermetally, the specimens that represent the best conditions are those produced with 125 and 150 W with 30 J/mm 3 , in order not compromising the SMA properties, and would allow microstructural evolution for the formation of the NiTi through heat treatment. Although the most favorable parameters, the NiTi system did not exhibited an austenitic matrix, and then the adoption of the proposed elementary powders mixture will be promising when followed by solution heat treatment, which is one of the works under development by our research group.

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Study on the junction zone of NiTi shape memory alloy produced by selective laser melting via a stripe scanning strategy

Cited by 21 publications

References 44 publications

Effect of Scanning Strategies on the Microstructure and Mechanical Properties of Inconel 718 Alloy Fabricated by Laser Powder Bed Fusion

Effect of Scanning Strategies on the Microstructure and Mechanical Properties of Inconel 718 Alloy Fabricated by Laser Powder Bed Fusion

Preparation and Electron-Beam Surface Modification of Novel TiNi Material for Medical Applications

Production of Cylindrical Specimens Based on the Ni-Ti System by Selective Laser Melting from Elementary Powders

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