H. Lu; C. Zhou; Y. Song; Y. Zhang; Y. Wu; F. Long; Y. Yao; J. Hao; Y. Chen; D. Yu; J.J. Schwiedrzik
Nature Communications 16 (2025) 211
Iron alloys, including steels and magnetic functional materials, are widely used
in capital construction, manufacturing, electromagnetic technology, etc.
However, they face the long-standing challenge of high coefficient of thermal
expansion (CTE), limiting the applications in high-precision fields. This work
proposes a strategy involving the in-situ formation of a nano-scale lamellar/
labyrinthine negative thermal expansion (NTE) phase within the iron matrix to
tackle this problem. For example, a model alloy, Fe-Zr10-Nb6, was synthesized
and its CTE is reduced to approximately half of the iron matrix. Meanwhile, the
alloy possesses a strength-plasticity combination of 1.5 GPa (compressive
strength) and 17.5% (ultimate strain), which outperforms other low thermal
expansion (LTE) metallic materials. The magnetovolume effect of the NTE
phase is deemed to counteract the positive thermal expansion in iron. The
high stress-carrying hard NTE phase and the tough matrix synergistically
contribute to the high mechanical properties. The interaction between the slip
of lamellar microstructure and the slip-hindering of labyrinthine microstructure
further enhances the strength-plasticity combination. This work shows the promise
of offering a method to produce LTE iron alloys with high mechanical properties.