Manufacturing and characterization of NiTi alloy with functional properties by selective laser melting

Shih Fu Ou, Bou Yue Peng, Yi Cheng Chen, Meng Hsiu Tsai

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

In this study, an optimal selective laser melting (SLM) process for manufacturing dense NiTi alloy with pseudoelasticity and shape-memory capability was proposed. The microstructure, phase-transformation temperature, shape memory capability, and pseudoelasticity were investigated by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and bending and tensile tests. NiTi powder with a particle size > 45 µm was selected for the subsequent SLM process, because it exhibited a Ni/Ti ratio of ~1 and a lower oxygen content than powders with smaller particle sizes. A thin-walled disk (0.48 mm thick) and cuboid samples (5 mm thick) were prepared for investigating the variation in the homogeneity of the microstructure. The thin-walled SLM-NiTi sample exhibited a marginally inhomogeneous microstructure between layers, and defects existed in the previously formed side. The cuboid SLM-NiTi sample was fabricated without undesirable secondary phases, and it exhibited a 100% shape-recovery rate under 2% bending strain and completely pseudoelastic under 3% strain. Also, the SLM-NiTi exhibited lower phase-transformation temperatures and a broader phase-transformation range than the original NiTi. The phase-transformation range can be reduced by annealing.

Original languageEnglish
Article number342
JournalMetals
Volume8
Issue number5
DOIs
Publication statusPublished - May 11 2018

Keywords

  • NiTi
  • Pseudoelasticity
  • Selective laser melting
  • Shape memory

ASJC Scopus subject areas

  • Materials Science(all)

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