【摘要】 利用Al-Ti-TiO2-Nb2O5体系的放热反应,原位热压合成了Nb掺杂Al2O3/TiAl复合材料。借助DTA结合XRD探讨了Al-Ti-TiO2-Nb2O5体系的反应过程,并采用XRD、OM和SEM研究了复合材料的物相组成及显微结构。结果表明:Al熔化的同时,体系发生了Al和Nb2O5的铝热反应,生成了NbO2和Nb等中间产物,并放出了较多热量,这些热量促使Ti和Al较早化合生成TiAl3,随即引发Al和TiO2较早的还原反应,进而促使材料在较低温度下致密烧结;产物由-γTiAl、α2-Ti3Al、Al2O3和NbAl3相构成,Al2O3颗粒分布于基体交界处,存在一定的团聚;Nb2O5的引入,对基体-γTiAl相和α2-Ti3Al相的的分布有一定的影响,使得基体晶粒细化,较好地改善了材料的力学性能。更多还原

【Abstract】 Nb-doped Al₂O₃/TiAl composites were fabricated by in-situ hot-pressing method with exothermic reaction of Al,Ti,TiO₂ and Nb₂O₅ powder.The reaction process was experimentally investigated by DTA and XRD,the phase composition and microstructure of composites were characterized by XRD,OM and SEM.The results indicate that thermal reaction between aluminum and Nb₂O₅ occurred with the melting of aluminum,some intermediate phases（NbO₂ and Nb） formed.And much reactive heat energy released in the processing,which could promote the earlier reaction of titanium and aluminum,subsequently the reaction of aluminum and TiO₂,and consequently the sintering of materials at relatively low temperature. The final phases of the composite are composed of γ-TiAl,α₂-Ti₃Al,Al₂O₃ and NbAl₃,the Al₂O₃ particles assemble on the boundary of matrix grains and slightly aggregate.The addition of Nb₂O₅ strongly influenced the distribution of γ-TiAl and α₂-Ti₃Al in the matrix,and matrix grains were also refined with increasing niobium content,which is beneficial to the mechanical property of composites.更多还原