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.
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.