4D PRINTING

4D-Printed Active
Metallic Structures

Multi-stage shape recovery in a U-shaped additively manufactured NiTi build piece using Laser Powder Bed Fusion (LPBF). Two “arms” of the piece activate their shape recovery at different temperatures, creating a location-dependent active response; The location-dependent active response is created by changing the LPBF processing at different sections of the build, which results in differences in the transformation temperatures in corresponding sections.

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Two different sets of LPBF processing parameters were used to process two different sections in a single Ni50.9Ti49.1 SMA U-shaped build piece. The two arms of the U-shape build piece were subsequently pre-formed at 0 °C in the martensite state. As the part is heated, the reverse transformation from martensite to austenite occurs, resulting in a two-stage shape change where different sections of the part activate the shape memory response at different temperature intervals and at different rates.

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