Title

Strengthening mechanism and micropillar analysis of high-strength NiTi–Nb eutectic-type alloy prepared by laser powder bed fusion

Document Type

Journal Article

Publication Title

Composites Part B: Engineering

ISSN

13598368

Volume

200

Publisher

Elsevier

School

School of Engineering

RAS ID

32072

Funders

National Natural Science Foundation of China National Key Research and Development Program of China National Basic Research Program of China

Comments

Liu, S., Han, S., Zhang, L., Chen, L. Y., Wang, L., Zhang, L., ... & Zhang, L. C. (2020). Strengthening mechanism and micropillar analysis of high-strength NiTi–Nb eutectic-type alloy prepared by laser powder bed fusion. Composites Part B: Engineering, 200, article 108358. https://doi.org/10.1016/j.compositesb.2020.108358

Abstract

© 2020 Elsevier Ltd Although laser powder bed fusion (LPBF) can produce complex structures with promising properties, there still exists a concern on the diversity in materials, especially composites, for LPBF. This work innovatively used NiTi and Nb powders to prepare NiTi–Nb eutectic-type alloy by LPBF, which provides a new method to prepare NiTi–Nb shape memory alloy and could be an alternative for tailoring microstructure. The semi-molten Nb particle phase was retained during LPBF, so that β-Nb and the eutectic structure display a gradient distribution in the Nb diffusion concentration. The heat treatment process (annealed at 850 °C for 0.5 h) makes NiTi–Nb samples have high yield strength (~1640 MPa), high compressive strength (~2380 MPa), and high compressive strain (~39%), which are superior to the corresponding ones of its as-built and as-cast counterparts. Large Nb phase particles with a size of 10–30 μm are retained and accelerated the formation of eutectic phase and β-Nb precipitate phase. Overall, the presence of β-Nb phase has a beneficial effect on the alloy, and a large number of intertwined dislocations and stacking faults around the β-Nb phase promote the formation of martensite under stress loading. The eutectic phase makes an important contribution to the high strength and plasticity of the NiTi–Nb alloy.

DOI

10.1016/j.compositesb.2020.108358

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