• International Journal of Extreme Manufacturing
  • Vol. 5, Issue 3, 35005 (2023)
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Author Affiliations
  • 1State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, People’s Republic of China
  • 2Faculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, People’s Republic of China
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    DOI: 10.1088/2631-7990/acd96f Cite this Article
    [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese]. Formation mechanism of inherent spatial heterogeneity of microstructure and mechanical properties of NiTi SMA prepared by laser directed energy deposition[J]. International Journal of Extreme Manufacturing, 2023, 5(3): 35005 Copy Citation Text show less

    Abstract

    Ni51Ti49 at.% bulk was additively manufactured by laser-directed energy deposition (DED) to reveal the microstructure evolution, phase distribution, and mechanical properties. It is found that the localized remelting, reheating, and heat accumulation during DED leads to the spatial heterogeneous distribution of columnar crystal and equiaxed crystal, a gradient distribution of Ni4Ti3 precipitates along the building direction, and preferential formation of Ni4Ti3 precipitates in the columnar zone. The austenite transformation finish temperature (Af) varies from .12.65 .C(Z = 33 mm) to 60.35 .C(Z = 10 mm), corresponding to tensile yield strength (σ0.2) changed from 120 ± 30 MPa to 570 ± 20 MPa, and functional properties changed from shape memory effect to superelasticity at room temperature. The sample in the Z = 20.4 mm height has the best plasticity of 9.6% and the best recoverable strain of 4.2%. This work provided insights and guidelines for the spatial characterization of DEDed NiTi.
    [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese]. Formation mechanism of inherent spatial heterogeneity of microstructure and mechanical properties of NiTi SMA prepared by laser directed energy deposition[J]. International Journal of Extreme Manufacturing, 2023, 5(3): 35005
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