Origin of premature fracture and enhancement of superelasticity in laser additively manufactured Ni-rich NiTi metamaterials

Zhaorui Yan, Jia Ning Zhu*, Yi Chieh Yang, Hans Brouwer, Ton Riemslag, Joerg R. Jinschek, Marcel Hermans, Jovana Jovanova, Vera Popovich

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Superelastic metamaterials have attracted significant attention recently, but achieving such functionality remains challenging due to partial superelasticity and premature fracture in additively manufactured components. To address these issues, this study investigates the premature fracture in Ni-rich NiTi metamaterials fabricated by laser powder bed fusion. A comparative analysis of two structures (Gyroid network and Diamond shell) reveals that the structural stability of bending- and stretching-dominated structures is reversed compared to typical elastic-plastic response, due to the tension-compression asymmetry of base NiTi. The premature fracture and partial superelasticity of these as-fabricated samples are attributed to low deformation ability for accommodating tensile stress. Based on these findings, a heat treatment introducing Ni4Ti3 precipitates was employed, successfully achieving macroscopic superelasticity in the NiTi metamaterials, with consistency between model prediction and experiments.

Original languageEnglish
Article number116558
Number of pages8
JournalScripta Materialia
Volume259
DOIs
Publication statusPublished - 2025

Keywords

  • Additive manufacturing
  • Metamaterials
  • NiTi
  • Shape memory alloys
  • Superelasticity

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