Dense alumina ceramics doped with 5 wt% 4CuO-TiO₂-2Nb₂O₅ composite sintering aids were obtained at low sintering temperatures of 950∼975 °C. The ceramic sintered at optimal condition shows good microwave dielectric properties (ε_r = 12.7, Q × f = 7400 GHz), high thermal conductivity (18.4 W/m K) and high bending strength (320 MPa). TEM and EDS analysis revealed that amorphous Cu-Ti-Nb-O interfacial films with nanometer thickness formed at the grain boundaries, which could provide paths of mass transportation for densification. Al³⁺ ions may be involved in mass transportation through substitution by Ti³⁺ and Ti⁴⁺ ions near the grain boundary during the sintering process. The accumulation of copper ions at the trigeminal grain boundary was observed. The migration and reaction of copper ions in grain boundaries may also play an important role in promoting mass transportation and low-temperature densification of alumina ceramics.

在950〜975°C的低烧结温度下获得了掺有5 wt％4CuO-TiO ₂ -2Nb ₂ O ₅复合烧结助剂的致密氧化铝陶瓷。在最佳条件下烧结的陶瓷表现出良好的微波介电性能（_εr = 12.7，Q×f = 7400 GHz），高导热率（18.4 W / m K）和高弯曲强度（320 MPa）。TEM和EDS分析表明，在晶界处形成了纳米厚度的非晶态Cu-Ti-Nb-O界面膜，可以为致密化提供大量的传输路径。Al ³⁺离子可能通过被Ti ³⁺和Ti ⁴⁺取代而参与质量传输烧结过程中晶界附近的离子。观察到三叉晶界处铜离子的积累。铜离子在晶界中的迁移和反应在促进氧化铝陶瓷的传质和低温致密化方面也可能起重要作用。