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Title: Additive manufacturing of NiTi shape memory alloys using pre-mixed powders
Authors: Tor, Shu Beng
Wong, Chee How
Wang, Chengcheng
Tan, Xipeng
Du, Zehui
Chandra, Shubham
Sun, Zhongji
Lim, Joel Choon Wee
Lim, Choon Seng
Keywords: Directed Energy Deposition
DRNTU::Engineering::Mechanical engineering
3D Printing
Issue Date: 2019
Source: Wang, C., Tan, X., Du, Z., Chandra, S., Sun, Z., Lim, C., … Wong, C. (2019). Additive manufacturing of NiTi shape memory alloys using pre-mixed powders. Journal of Materials Processing Technology, 271152-161. doi:10.1016/j.jmatprotec.2019.03.025
Series/Report no.: Journal of Materials Processing Technology
Abstract: This work presents a comparative study on the in-situ alloying of NiTi shape memory alloys (SMAs) by directed energy deposition (DED), selective laser melting (SLM) and selective electron beam melting (SEBM) processes using pre-mixed Ni-Ti powders. The influence of process parameters on the microstructural homogeneity, phase formation and thermomechanical properties of NiTi alloy has been systematically studied. DED could build solid NiTi alloys with good interlayer fusion and phase transformation characteristics. However, a substantial amount of uniformly dispersed Ti2Ni intermetallics can embrittle this material. SLM-built NiTi parts show a tradeoff between microstructural inhomogeneity and keyhole defects when the energy densities are varied. In addition, the strong exothermic reaction in Ni-Ti powder mixtures during printing can disturb the melt pool, making it challenging to elaborate this material and obtain desired phases by using SLM. Moreover, SEBM is found to be unsuitable to in-situ synthesize this highly reactive material due to the lack-of-fusion vs. powder-ignition dilemma in the mandatory preheating step. It is suggested to adopt DED to in-situ alloy NiTi parts when using the elementally blended powders as feedstocks.
ISSN: 0924-0136
DOI: 10.1016/j.jmatprotec.2019.03.025
Rights: © 2019 Elsevier B.V. All rights reserved. This paper was published in Journal of Materials Processing Technology and is made available with permission of Elsevier B.V.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:MAE Journal Articles
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