Superelastic NiTi Functional Components by High-Precision Laser Powder Bed Fusion Process: The Critical Roles of...

Area of Science:

• Materials Science
• Manufacturing Engineering
• Biomedical Engineering

Background:

• Additive manufacturing (AM), particularly laser powder bed fusion (LPBF), enables complex component fabrication.
• Nickel-Titanium (NiTi) is a smart material with superelastic and shape-memory properties vital for biomedical applications.
• NiTi properties are highly sensitive to microstructure, which is dictated by LPBF process parameters.

Purpose of the Study:

• To establish a process optimization methodology for intricate NiTi components using LPBF.
• To determine optimal LPBF parameters for achieving desired superelasticity in NiTi robotic cannula tips.
• To investigate the influence of wall thickness on energy density requirements for NiTi structures.

Main Methods:

• Confirmed the process window for LPBF of NiTi by printing thin walls and bulk structures.
• Utilized a Gyroid-type sheet triply periodic minimal-surface (G-TPMS) structure as a standard sample for precise parameter optimization.
• Analyzed the effect of wall thickness on optimal energy density by varying G-TPMS structure dimensions.

Main Results:

• Established processing guidelines for intricate NiTi components via LPBF.
• Identified that for G-TPMS structures with wall thickness below 130 μm, the optimal energy density shifts from 167 J/m³ to 140 J/m³.
• Demonstrated that reduced cooling rates in thinner walls influence the optimal energy density.

Conclusions:

• A novel process optimization methodology for LPBF of NiTi has been developed.
• Processing guidelines are provided for manufacturing intricate NiTi components with tailored superelastic properties.
• Understanding the relationship between wall thickness and energy density is critical for optimizing NiTi AM parts.