A High Thermal Conductivity Kovar Alloy via Chemical Tailoring

Achieving high thermal conductivity while maintaining thermal expansion compatibility is crucial for efficient heat dissipation and long-term reliability in electronic devices; yet, it remains rare in metallic systems. Here, through chemical tailoring in high-symmetry face-centered cubic Fe–Ni alloys, we design a Fe 55.6 Ni 27.3 Cu 17.1 ternary alloy to achieve both low thermal expansion ( α l = 5.37 × 10 –6 K –1, 112–492 K) and high thermal conductivity (18.24 W·m –1 ·K –1 at room temperature). Cu substitution shifts the Fe majority-spin d band top-edge toward the Fermi level, strengthening the magneto-volume effect and reducing thermal expansion, while simultaneously increasing the s band electron density at the Fermi level to enhance free-electron transport and boost thermal conductivity. These results highlight that chemical tailoring provides an effective strategy for enhancing thermal and magnetic properties, offering both a theoretical foundation and a practical pathway for designing high-performance electronic packaging alloys.