The effect of interface reaction on the thermal and mechanical properties of Mn_3.2Zn_0.5Sn_0.3N/Al composites

The salient feature of low-expansion metal matrix composites is their dimensional stability. Due to the limitation of the performance of the reinforcement, the current low-expansion metal matrix composite materials cannot achieve both low expansion and high mechanical strength at the same time. With its extremely negative thermal expansion behavior and metallic characteristics, the anti-perovskite manganese nitrogen compound can be used as an ideal thermal expansion inhibitor to prepare high mechanical strength low-expansion composite materials. In the present work, fully-dense Mn_3.2Zn_0.5Sn_0.3N/Al composites with low thermal expansion and high strength have been successfully fabricated by pressure infiltration. The effects of fabricating temperature on the microstructure, thermal expansion and mechanical properties of the Mn_3.2Zn_0.5Sn_0.3N/Al composites have been discussed. Several interfacial reactions were caused by the high fabrication temperature (750 °C and 800 °C). Lower fabrication temperature (700 °C) was used to obtain a well-controlled interface composite with low thermal expansion (α = 6.5 × 10⁻⁶ K⁻¹), high compression strength (481 MPa) and hardness (612 HV). A modified theoretical model has also been used to analyze the thermal expansion behavior of the composites.