球磨工艺对原位合成Al_(2)O_(3)/TiAl复合材料性能的影响

Effect of ball milling process on properties of in-situ synthesizedAl_(2)O_(3)/TiAl composites

采用不同的球磨时间和球料比,实现了Ti、Al、TiO2和Nb2O5粉末的机械合金化,并以其为原料采用放电等离子烧结(SPS)技术制备了Al_(2)O_(3)/TiAl复合材料。利用扫描电镜(SEM)和X射线衍射(XRD)等对球磨后粉末的形貌、大小、相组成以及其烧结后复合材料的组织进行了观察分析。结果表明:球磨时间和球料比对粉体的形貌、尺寸和均匀度均存在影响,但延长球磨时间有利于粉体的机械合金化,而球料比对合金化程度影响较小。将球料比5∶1,球磨6 h后的粉体在1000℃、40 MPa真空环境下烧结10 min,制备了Al_(2)O_(3)/TiAl复合材料,其显微组织主要由γ-TiAl、α2-Ti3Al、Al3Nb,以及分布在基体晶界处的Al_(2)O_(3)组成,压缩强度为1476 MPa,硬度为490 HV。

Mechanical alloying of Ti,Al,TiO2 and Nb2O5 powders was realized by ball milling for different time with different ball-to-powder ratios,and Al_(2)O_(3)/TiAl composites were prepared by spark plasma sintering(SPS)using the mechanical alloying powders as raw materials.The morphology,size,phase composition of the mechanical alloying powders and the microstructure of the composites were observed and analyzed by means of scanning electron microscopy(SEM)and X-ray diffraction(XRD).The results show that the ball milling time and ball-to-powder ratio have effects on the morphology,size and uniformity of the powder,but prolonging the ball milling time is conducive to the mechanical alloying of the powders,while the ball-to-powder ratio has little effect on the mechanical alloying degree.The Al_(2)O_(3)/TiAl composites are prepared by SPS at 1000℃for 10 min under vacuum pressure of 40 MPa using mechanical alloying powders which prepared by ball milling for 6 h with ball-to-powder ratio of 5:1 as raw materials,and its microstructure is mainly composed ofγ-TiAl,α2-Ti3Al,Al3Nb,and Al_(2)O_(3)distributed at the grain boundary of the matrix,the compressive strength is 1476 MPa and the hardness is 490 HV.