ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2026 37 FEATURE Optimization of the binder chemistry and debinding process has reduced carbon by approximately one order of magnitude relative to the earliest trials, and this remains the focus of ongoing work. WHICH REQUIREMENTS DOES THE APPLICATION IMPOSE? The comparison between measured properties and standard limits raises a question that extends beyond process development. ASTM F2063 was written for wrought semi-finished products, bar, sheet, and tube, destined primarily for implants whose thin struts sustain hundreds of millions of load cycles. Its interstitial limits guard against the fatigue consequences of carbide and oxide inclusions under exactly those conditions. Whether the same limits are the appropriate acceptance criteria for a sintered instrument mechanism, a compression-loaded orthopedic lattice, or an industrial actuator is not self-evident. A delivery- system component is qualified through its own functional evidence: transformation window, plateau stresses, fatigue life at the amplitudes of its duty cycle, corrosion behavior, and, where applicable, biocompatibility endpoints. The data presented here illustrate the point. Material that exceeds the wrought chemistry limits nevertheless meets the mechanical reference values of ASTM F2516 and places its transformation window where the application requires it. This is not an argument for relaxing implant requirements; the fatigue and biocompatibility consequences of inclusion populations in thin, cyclically loaded struts are real and well documented. It is an argument for deriving requirements from the application rather than inheriting them from the semi-finished products of an earlier manufacturing era. Where the inclusion population of a sintered microstructure proves compatible with the loads and environment of a given device class, requirement profiles defined at device level would open these applications earlier than a blanket transfer of wrought-material chemistry. Developing such profiles is a task for the SMA community as a whole, standards bodies, device manufacturers, and material developers together. OUTLOOK Whether sinter-based additive manufacturing will replace established NiTi routes is an open question, and it deserves to be treated as one. For the geometries that wire and tube already serve well, those processes are qualified, economical, and thoroughly understood. For the geometries that they cannot produce, there is no incumbent to displace. Between these poles lies a wide field in which the answer is not settled: components that are today assembled from several conventionally made parts because no single part could be manufactured, and devices whose present form reflects the historical availability of wire and tube more than the demands of their function. The productive stance is to re-examine these cases individually, asking whether the established route is required by function or retained by habit. The basis for that reexamination is developing quickly, and it advances fastest where materials work and device requirements meet. Progress toward qualified sintered NiTi will come from defining application-level requirement profiles, testing them against real device concepts, and feeding the results back into process development. The authors pursue this deliberately as cooperative work: Engineers who recognize an application in the geometries this route makes possible, in delivery systems, orthopedics, actuation, or elsewhere, are invited to put its boundaries to the test. ~SMST For more information: Lucas Vogel, CEO, MetShape GmbH, Tiefenbronner Str. 59, 75175, Pforzheim, Germany, +49.7231.3744187, lucas.vogel@metshape.de, www.metshape.com. References 1. T.W. Duerig, A.R. Pelton, and D. Stöckel, An Overview of Nitinol Medical Applications, Materials Science and Engineering: A, 273-275, p 149-160, 1999. 2. T.C. Dzogbewu and D.J. de Beer, Additive Manufacturing of NiTi Shape Memory Alloy and Its Industrial Applications, Heliyon, 10, e23369, 2024. 3. ASTM F2063, Standard Specification for Wrought Nickel-Titanium Shape Memory Alloys for Medical Devices and Surgical Implants, ASTM International. 4. ASTM F2516-22, Standard Test Method for Tension Testing of Nickel-Titanium Superelastic Materials, ASTM International. 5. Y. Cohen, et al., Sinter-based Additive Manufacturing of Ni-Ti Shape Memory Alloy, SSRN Electronic Journal, February 5, 2023. Fig. 3 — Tensile loading–unloading response of three heat treated LMM NiTi samples, showing development of the superelastic plateau and retained strain below 1%.
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