Sintering pressure effect on the performances of near-zero thermal expansion xLFCS/Cu metal matrix composites

Abstract

Metal-matrix materials exhibiting near-zero thermal expansion (NZTE) behavior are urgently required in electronic packaging and precision instruments. However, the practical application of this material faces some challenges, such as a narrow operating temperature, low thermal conductivity, and weak mechanical properties. This study investigates the effect of sintering pressure on the microstructural evolution of multicomponent negative-thermal-expansion La(Fe, Co, Si)13 reinforced Cu composites via spark plasma sintering (SPS). Near-zero thermal expansion was obtained over a wide range of temperature between 200 and 320 K by using multicomponent reinforcements. The porosity decreased from 4.7% to 0.6% when the sintering pressure increased from 50 to 150 MPa. As the sintering pressure increases, the agglomerated Cu particles gradually transform into continuous Cu networks. The combination of a dense structure and continuous Cu networks leads to a large maximum compressive strength of 758 MPa and a high thermal conductivity of 56.2 Wm−1K−1, which are the best comprehensive properties of wide-temperature-range NZTE composites ever reported. This study provides an effective method for resolving the tradeoff between low thermal expansion and high strength in most NZTE materials.