Additively manufactured multi-functional metamaterials: low coefficient of thermal expansion and programmable Poisson’s ratio

ABSTRACT

By using Invar 36 alloy as the constituent material, a series of multi-functional metamaterials, integrating low coefficient of thermal expansion (CTE) and programmable Poisson’s ratio (PR), were originally designed and additively manufactured by laser powder bed fusion (PBF-LB). The densification, relative density, microstructures, CTE and PR were systematically characterised and analysed by experiments and numerical modelling. Specifically, the fabricated metamaterials demonstrate uniform microstructures, resulting in isotropic low CTEs ranging from 1.79 to 1.85 ppm/°C. Besides, the designed metamaterials achieve PR tuning in the range of −0.54∼+0.58, which is close to the theoretical predictions, confirming the PR programmability. The underlying mechanism is disclosed that the variable θ₁ dominates the transverse deformation behaviour of the metamaterial, achieving programmable PR. Summarily, these metamaterials achieve the integration of the low CTE and programmable PR, and provide a wider operating temperature range and superior mechanical performances than polymer-based multi-functional metamaterials, exhibiting a broader application prospect.

KEYWORDS:

• Metamaterial
• coefficient of thermal expansion
• Poisson’s ratio
• Invar 36 alloy
• laser powder bed fusion

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data obtained or analysed in this work are included in this manuscript.

Additional information

Funding

The authors are grateful for the support of the National Natural Science Foundation of China (Grant No. 12372133). This research is also supported by the Science and Technology Innovation Program of Hunan Province (Grant No. 2021RC30306).