In this paper, we have designed a Al₂O₃/(NbTaMoW)C composite by in-situ exothermic reaction, which opened a new field to explore HEC matrix composites. The Al₂O₃/(NbTaMoW)C composite was synthesized at 1600 °C using Nb, Ta, W, MoO₃, Al and graphite powders as raw materials, and the thermite of Al + MoO₃ as heat source provides additional energy for the formation of composites. As-prepared composites with relative density 98.5% only exhibited two phases including a high entropy carbide of (NbTaMoW)C and Al₂O₃ phases, and Al₂O₃ randomly distributed within high entropy matrix. Phase boundary between (NbTaMoW)C and Al₂O₃ was a noncoherent interface, resulting in a moderate interfacial bonding strength which was beneficial to both flexural strength and fracture toughness. Moreover, Al₂O₃ and HEC form an interesting interlocking structure and a grain size varies from 1 μm to 10 μm due to the inhomogeneous temperature distribution introduced by the in-situ exothermic heat. By taking advantages of these special structures, the composites exhibited significantly enhanced mechanical properties compared to (NbTaMoW)C. The flexural strength of composites was up to 530 MPa, and the fracture toughness was 4.5 MPa m^1/2. The main strengthening mechanism is second phase strengthening and the presence interlocking structure releases stress intensity at crack tip.

本文通过原位放热反应设计了Al ₂ O ₃ /（NbTaMoW）C复合材料，为探索HEC基复合材料开辟了新领域。以Nb，Ta，W，MoO ₃，Al和石墨粉为原料，在1600°C合成Al ₂ O ₃ /（NbTaMoW）C复合材料，而Al + MoO _3的热铝矿为热提供了额外的能量。复合材料的形成。相对密度为98.5％的复合材料仅表现出两相，包括（NbTaMoW）C和Al ₂ O ₃相的高熵碳化物，以及Al ₂ O ₃在高熵矩阵内随机分布。（NbTaMoW）C和Al ₂ O ₃之间的相界是不连贯的界面，导致适度的界面结合强度，这既有利于弯曲强度，也有利于断裂韧性。此外，Al ₂ O ₃和HEC形成了有趣的互锁结构，并且由于原位放热引入的温度分布不均匀，晶粒尺寸从1μm到10μm不等。通过利用这些特殊的结构，与（NbTaMoW）C相比，复合材料的机械性能显着增强。复合材料的弯曲强度高达530 MPa，断裂韧性为4.5 MPa m ^1/2。主要的强化机制是第二阶段强化，存在的互锁结构释放裂纹尖端的应力强度。