A Kagome Metallic Composite Realizes Mechanically Axial Zero Thermal Expansion up to 800 K

Manipulating the crystal structure and microstructure is fundamentally paramount for designing advanced materials with enhanced functionalities. Kagome-lattice metals attracted considerable attention due to desirable electronic and magnetic properties but are rarely considered for application as structural materials. In this study, a concept of kagome composite is proposed to realize mechanically zero thermal expansion (ZTE) alloy over a wide temperature window, exemplified by the Lu-Fe-Co ternary alloys prepared by two-step synthesis. Using magnetic Co doping, the kagome lattice magnetic order is stabilized in the parent hexagonal Lu₂Fe₁₇ structure, and its thermal expansion regulated simultaneously. By in situ precipitation of the α-(Fe/Co) phase in the matrix, a soft/hard heterogeneous structure emerges and an ultra-wide temperature window axial ZTE composite (α_l = +0.98 × 10^-6 K^-1, 110-800 K) with good compressive strength (1.11 GPa) is achieved. This work opens up the prospect of kagome intermetallic composite in the integration of structure and function.