掺杂对Al_2O_3/TiAl复合材料性能的影响

本研究采用Ti-Al-TiO2-La2O3体系,通过热压烧结工艺原位合成了Al2O3/TiAl复合材料.借助X射线衍射(XRD)、扫描电镜(SEM)等分析研究了材料的物相组成和微观组织结构,同时分别将掺杂La2O3和掺杂Fe2O3对合成Al2O3/TiAl复合材料微观结构和力学性能的影响进行了对比.结果表明:掺杂La2O3合成的Al2O3/TiAl复合材料基体尺寸相对掺杂Fe2O3合成产物较小,分散更加均匀,致密度更高.当La2O3掺杂量为3.93wt%时,Al2O3/TiAl复合材料的抗弯强度和断裂韧性达到最大值,分别为701.95MPa和7.79MPa·m1/2.由于稀土氧化物具有对基体和增强颗粒的净化,细化晶粒等作用,因此提高了TiAl基体与Al2O3增强颗粒结合强度,所以掺杂La2O3合成材料的力学性能相比掺杂Fe2O3合成的产物较高.

Effect of doping on the properties of Al2 O3/TiAl composites

Al2O3/TiAl composites were successfully synthesized by hot pressing based on the TiAl-TiO2-La2O3 system .The phase composition and microstructure of composites were characterized by X-ray diffraction analysis （XRD） and scanning electron microscopy （SEM ） . The respective effects of La2O3 and Fe2O3 addition on microstructure and mechanical proper-ties of the prepared composites were also compared .The results indicate that ,in contrast to the Al2O3/TiAl composite with Fe2O3 addition ,the matrix grain size of the composite doped with La2O3 is smaller and the Al2O3 particles disperse more uniformly .Meanwhile ,the densi-ty of the latter is higher .When the La2O3 content is 3 .93 w t% ,the products possess the maximum value of 701 .95 MPa和7 .79 MPa · m1/2 for the flexural strength and fracture toughness ,respectively .The bonding strength of TiAl matrix and Al2O3 reinforced particles increases due to the clean-up effect of the rare earth oxide on the interface of the two phases .Consequently ,the composite doped with La2O3 addition has more optimal mechanical proper-ties than that with Fe2O3 addition .