Influence of freezing temperature on microstructure and properties of lamellar MoCu composites fabricated by ice-templating method

Abstract

In this paper, lamellar MoCu composites with alternating distribution of Mo phase and Cu phase were prepared by ice-templating and infiltration methods. Briefly, a homogeneous slurry containing Mo powder (2–3 μm), polyvinyl alcohol (PVA), and deionized water was ball-milled, directionally frozen at controlled temperatures (−10 °C to −70 °C), freeze-dried, and then thermally decomposed to form a porous Mo skeleton. Finally, the skeleton was infiltrated with molten Cu at 1350 °C to obtain the dense composite. With the decrease of the freeze temperature, the thickness of the lamellar MoCu composite gradually decreases from 34 μm (−10 °C) to 5 μm (−70 °C), the number of interfaces gradually increases, and the hardness of the lamellar MoCu composite surface perpendicular to the lamellar direction becomes higher and higher (the maximum hardness value can reach 160.4 HV_0.3, a 33.3 % enhancement compared to conventional homogeneous MoCu composites). The thermal conductivity parallel to lamellae decreases from 260.7 W/m·K (−10 °C) to 249.3 W/m·K (−70 °C), while the thermal expansion coefficient parallel to lamellae reduces from 1.12 × 10⁻⁵/K (−10 °C) to 9.36 × 10⁻⁶/K (−70 °C). The thermal conductivity parallel to the lamellar direction is higher than that perpendicular to the lamellar direction, and the average thermal expansion coefficient is lower than that perpendicular to the lamellar direction. The thermal conductivity and thermal expansion coefficient of the lamellar MoCu composite parallel to the lamellar direction achieve a good match, demonstrating its potential for advanced thermal management applications.