In humanity’s quest for clean energy, controlled nuclear fusion—often hailed as an “artificial sun”—is regarded as the ultimate solution to the global energy crisis. Realizing this vision hinges on generating ultra-strong magnetic fields capable of confining plasma at temperatures exceeding 100 million degrees Celsius. At the heart of this endeavor lies second-generation high-temperature superconducting (HTS) tapes—and their foundational component: the high-temperature superconducting substrate, which determines the success or failure of the entire system.
Superconducting materials exhibit zero electrical resistance. However, conventional superconductors require operation at extremely low liquid helium temperatures (–269°C), making them prohibitively expensive. The emergence of high-temperature superconductors—such as REBCO (Rare Earth Barium Copper Oxide)—has changed this paradigm. These materials have critical temperatures above that of liquid nitrogen (–196°C), drastically reducing cooling costs while maintaining excellent current-carrying capacity even under intense magnetic fields.
Yet, high-temperature superconductors are ceramic oxides—brittle and difficult to process. How can such a fragile ceramic be transformed into a flexible tape suitable for winding large-scale magnets? The answer lies in the HTS substrate. Typically made from Hastelloy (a nickel-based superalloy), this substrate acts like the reinforced concrete foundation of a building. On its surface, researchers deposit multiple layers—buffer layers followed by the superconducting layer—to create a sophisticated multilayer composite structure.
The HTS substrate is far more than just mechanical support; it is critical to performance. Its surface roughness directly affects the crystalline alignment of the overlying superconducting layer. If the substrate surface is uneven, the superconductor cannot form a well-ordered crystal lattice, severely degrading its current-carrying capability. An ideal substrate must be mirror-smooth, with a surface roughness typically below 20 nanometers.
Moreover, the substrate must withstand immense electromagnetic forces. In fusion devices, superconducting magnets operate under extreme magnetic fields, generating Lorentz forces powerful enough to tear apart ordinary metals. Therefore, the substrate must possess exceptional yield strength and fatigue resistance. For instance, Hastelloy used in these applications must achieve a tensile strength exceeding 1,900 MPa at liquid nitrogen temperatures—equivalent to supporting 190 metric tons on an area the size of a fingernail.
Because of its pivotal role, the HTS substrate has long been considered a core technological bottleneck in advanced manufacturing. While China has ranked among the world leaders in the application of second-generation HTS materials, it historically relied on imported substrates—costly and subject to supply instability. This situation is now changing, thanks to coordinated efforts between domestic research institutions and enterprises.
Ningbo Yongcheng Metal Materials Technology Co., Ltd. is actively advancing in this field through independent R&D, focusing on overcoming the technical challenges of producing ultra-thin Hastelloy strips. By mastering the precision rolling process for Hastelloy ultra-thin tapes, the company is providing critical raw material support for the localization of HTS substrates—helping bring the “artificial sun” closer to illuminating homes around the world.
