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Zero thermal expansion (ZTE) alloys with high mechanical response are crucial for their practical usage. Yet, unifying the ZTE behavior and mechanical response in one material is a grand obstacle, especially in multicomponent ZTE alloys. Herein, we report a near isotropic zero thermal expansion (αl = 1.10 × 10−6 K−1, 260–310 K) in the natural heterogeneous LaFe54Co3.5Si3.35 alloy, which exhibits a super-high toughness of 277.8 ± 14.7 J cm−3. Chemical partition, in the dual-phase structure, assumes the role of not only modulating thermal expansion through magnetic interaction but also enhancing mechanical properties via interface bonding. The comprehensive analysis reveals that the hierarchically synergistic enhancement among lattice, phase interface, and heterogeneous structure is significant for strong toughness. Our findings pave the way to tailor thermal expansion and obtain prominent mechanical properties in multicomponent alloys, which is essential to ultra-stable functional materials. Zero thermal expansion materials play an increasingly important role in modern high-precision applications, but they are relatively scarce. Here, the authors achieve an isotropic zero thermal expansion with a very high toughness by manipulating chemical partitioning in chemically complex alloys. [ABSTRACT FROM AUTHOR]

Zero thermal expansion (ZTE) alloys possess unique dimensional stability, high thermal and electrical conductivities. Their practical application under heat and stress is however limited by their inherent brittleness because ZTE and plasticity are generally exclusive in a single-phase material. Besides, the performance of ZTE alloys is highly sensitive to change of compositions, so conventional synthesis methods such as alloying or the design of multiphase to improve its thermal and mechanical properties are usually inapplicable. In this study, by adopting a one-step eutectic reaction method, we overcome this challenge. A natural dual-phase composite with ZTE and plasticity was synthesized by melting 4 atom% holmium with pure iron. The dual-phase alloy shows moderate plasticity and strength, axial zero thermal expansion, and stable thermal cycling performance as well as low cost. By using synchrotron X-ray diffraction, in-situ neutron diffraction and microscopy, the critical mechanism of dual-phase synergy on both thermal expansion regulation and mechanical property enhancement is revealed. These results demonstrate that eutectic reaction is likely to be a universal and effective method for the design of high-performance intermetallic-compound-based ZTE alloys. Zero thermal expansion alloys have unique dimensional stability but suffer from inherent brittleness and compositional sensitivity. Here the authors present the one-step eutectic reaction approach to produce a dual-phase alloy with an axial zero expansion and promising mechanical properties. [ABSTRACT FROM AUTHOR]

Low thermal expansion alloy plays a unique role in high precision instruments and devices owing to its size stability under thermal shocks. However, a low thermal expansion generally produces a poor mechanical performance, such as brittleness and low fracture resistance, which is a bottle-neck for their applications as functional materials. Here, we demonstrate a novel intermetallic compound-based dual-phase alloy of Er-Fe-V-Mo with excellent structural and functional integrity achieved by precipitating a ductile phase in the hard-intermetallic matrix with large magnetovolume effect. It is found that the compound with 12.8 ± 0.1vol% precipitate phase improves the alloy's strength and toughness by one order of magnitude, while keeping a low bulk coefficient of thermal expansion (1.87±0.02 × 10−6 K −1) over a wide temperature range (100 to 493 K). The combined analyses of real-time in-situ neutron diffraction, synchrotron X-ray diffraction, and microscopy reveal that both the thermal expansion and the mechanical properties of the precipitate phase are coupled with the matrix phase via semi-coherent interfacial constraint; more importantly, the precipitate phase undergoes a pronounced strain hardening with dislocation slips, which relieves the stress localization and thus hinders the microcrack propagation in the intermetallic matrix. Moreover, the alloys are easy to fabricate and stable during thermal cycling with great application potentials. This study shed light on the development of low thermal expansion alloys as well as the implications to other high-performance intermetallic-compound-based material design. Image, graphical abstract [ABSTRACT FROM AUTHOR]