Mixing Enthalpy Optimized Zero Thermal Expansion With High Compressive Strength and Thermal Conductivity

Zero thermal expansion (ZTE) alloys hold great promise for applications in precision instruments, yet are severely limited by intrinsic brittleness and low thermal conductivity. Herein, enabled by optimizing mixing enthalpy, we report on a dual‐phase metallic composite that shows ZTE (α l = +0.6 × 10 −6 K −1 ) over a wide temperature range of 200–320 K together with high compressive strength (922 MPa) and thermal conductivity (23.2 W·m −1 ·K −1 ). Strong negative mixing enthalpies stabilize the Fe‐based Laves phase with giant room‐temperature negative thermal expansion (NTE, α V = −48 × 10 −6 K −1 , 280–330 K) in Hf 0.875 Ta 0.075 Nb 0.05 Fe 2 (HTNF), and positive mixing enthalpy drives phase separation between Cu and HTNF. Neutron powder diffraction reveals that the NTE of the ferromagnetic HTNF originates from the magnetovolume effect driven by substantial variations in local magnetic moments. The ZTE of the composite is achieved by mutual compensation of lattice expansions between the two phases. Coexistence of hard and soft natural dual phases thus yields such high compressive strength. This work gives an effective strategy for achieving ZTE alloys together with good mechanical properties and thermal conductivity.