Chinese Researchers Develop Iron-Based Substrate for Superconducting Tapes

Researchers at the Chinese Academy of Sciences Technical Institute of Physics and Chemistry have engineered a novel iron-based alloy substrate for second-generation high-temperature superconducting (2G-HTS) tapes, People's Daily reported. Tested by downstream manufacturers on a 12-millimeter tape, the material achieved a critical current of 647 amperes at 77 Kelvin under zero magnetic field. By replacing nickel-heavy Hastelloy C276, the new substrate cuts raw material costs to roughly one-fourth while delivering higher yield strength and improved deformation tolerance.

Second-generation high-temperature superconducting tapes are vital components for commercial fusion reactors, advanced power transmission, and particle accelerators. Traditionally, these tapes rely on Hastelloy C276, an expensive nickel-rich alloy whose mechanical properties have approached practical limits after 30 years of development. Reducing substrate raw material expenses by 75 percent while strengthening the mechanical skeleton could remove a key cost bottleneck hindering the large-scale industrialization of superconducting systems.

Researchers at the Technical Institute of Physics and Chemistry under the Chinese Academy of Sciences (CAS) have developed a novel iron-based alloy substrate for second-generation high-temperature superconducting (2G-HTS) tapes, according to a report by People's Daily. Following more than three years of development, downstream industrial partners successfully fabricated silver-plated superconducting tapes using the new substrate, reaching a critical current of 647 amperes under zero magnetic field at 77 Kelvin on a 12-millimeter-wide tape. Second-generation HTS tapes are viewed as critical building blocks for high-magnetic-field and high-power applications, including magnetic confinement fusion reactors, superconducting power transmission, and particle accelerators. In multi-layered 2G-HTS tape architectures, the metallic substrate functions as a structural skeleton that bears mechanical loads. For decades, the industry has relied almost exclusively on Hastelloy C276, a nickel-based superalloy containing over 50 percent nickel, alongside costly alloying elements such as molybdenum (approximately 16 percent), tungsten (3 percent), and cobalt (2.5 percent), with iron comprising only about 5 percent. Because of this composition, Hastelloy remains expensive. Furthermore, after roughly three decades of refinement, its mechanical performance has approached its physical ceiling. The research team, led by Li Laifeng and Shi Li at the CAS institute, designed an alternative composition consisting primarily of iron. According to the report, raw material costs for the new iron-based substrate are roughly one-fourth those of Hastelloy. Beyond cost reductions, tapes manufactured with the iron-based alloy substrate demonstrated superior mechanical and electromagnetic properties under identical processing conditions. The resulting superconducting tapes exhibited a substantial increase in yield strength compared to Hastelloy-based counterparts, alongside superior resistance to deformation. The new substrate also demonstrated lower relative magnetic permeability and lower electrical resistivity than Hastelloy. The research team noted that the lower substrate cost and improved high-field tolerance offer distinct advantages as the global market for high-temperature superconductors expands, though details regarding commercial-scale continuous production yields and the specific downstream manufacturers involved have yet to be disclosed.