Synthesis of TiAl based alloy by mechanical milling, warm pressing and reactive sintering
(1.山东省威海市哈尔滨工业大学材料科学与工程学院2.School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: The synthesis process TiAl based alloy by mechanical milling, warm pressing and reactive sintering was investigated. The microstructure of Ti-Al mixture powders milled was analyzed by backscattering electron image （BSE）. Then, the powders were warmly pressed in a vacuum hot-pressing device and reactively sintered at different temperatures for different times, the microstructures of TiAl based alloys after sintering were analyzed by scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and optical microscopy（OM）. The compositions of all stages were also analyzed by X-ray diffraction（XRD）. The results show that warm pressing can increase the relative densities of Ti-Al powder billets obviously. The billets warmly pressed with high relative density can be transformed into near fully-densified TiAl based alloy through pre-sintering at low temperature and sintering at high temperature for appropriate time, and the microstructure of the TiAl based alloy is the typical lamellar structure composed of γ-TiAl and α2-Ti3Al.
Key words: TiAl based alloy； mechanical milling； warm pressing； reactive sintering； lamellar structure