A strong and ductile Super Kovar alloy via fully coherent nanoprecipitates.

Authors

Chengyi Yu, Yujie Chen, Huihui Zhu, Yunxiang Yang, Yin Zhang, Lin Gu, Sergii Khmelevskyi, Kenichi Kato, Ke An, Dunji Yu, Yan Chen, Xiaobai Ma, Wenyun Yang, Dierk Raabe, Xianran Xing

Published in

Science advances. Volume 12. Issue 35. Pages eaeh4562. Aug 28, 2026. Epub Aug 28, 2026.

Abstract

Emerging high-precision technologies demand materials with exceptional dimensional stability and mechanical robustness, as even microscopic thermomechanical deformation can cause functional failure. However, a fundamental trilemma exists: High strength, ductility, and low thermal expansion are mutually exclusive, as strengthening-induced lattice distortions compromise the spin-lattice coupling, which is essential for low thermal expansion. Here, we overcome this trilemma by designing "Super Kovar," an Fe-Ni-Co-Al-Ta alloy, featuring fully coherent nanoprecipitates. It unifies a 1.0-gigapascal ultimate tensile strength and ∼39% elongation with a Kovar-grade thermal expansion of 3.81 × 10^-6 K^-1 (100 to 410 K). The key is a dense dispersion of L1₂ nanoprecipitates that form an almost strain-free coherent interface with the ferromagnetic matrix. Beyond providing precipitation strengthening, these coherent interfaces suppress intrinsic phonons of nanoprecipitates via elastic coupling while avoiding magnetic domain pinning to preserve the Invar effect of the matrix. This reduces the thermal expansion of the precipitates by 56% and achieves a fourfold enhancement in the strength-ductility product, establishing a paradigm for dimensionally stable, ultrastrong alloys.

PMID:
42664320
Bibliographic data and abstract were imported from PubMed on 29 Aug 2026.

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