Synthesis of TiAl-Ti2AlN composites by in-situ crystallization
(1.陕西省咸阳市陕西科技大学材料科学与工程学院
2.陕西省西安市西安交通大学材料力学行为的影响国家重点实验室
3.State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
4.School of Materials Science and Engineering, Shaanxi University of Science and Technology, Xianyang 712081, China)
2.陕西省西安市西安交通大学材料力学行为的影响国家重点实验室
3.State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
4.School of Materials Science and Engineering, Shaanxi University of Science and Technology, Xianyang 712081, China)
Abstract: The amorphization process during mechanical alloying (MA) was investigated for the Ti-50%/Al (mole fraction) powder mixtures with no special protection conditions. During the milling process, with the milling time prolonging, the metallic powder Ti and Al were finely mixed, gradually, aluminum completely dissolved into titanium to form an Ti(Al) hcp supersaturated solid solution, and finally, transformed to the amorphous phase after milled for about 39 h. As a result of heat treatment in hot press sintering processing for the mechanically alloyed amorphous powders in vacuum, a submicrostructure intermetallics of TiAl/Ti2AlN composite can be produced by in-situ crystallization. Furthermore, the structure evolution, phase formation and transformation during the heat treatment were also investigated by X-ray diffractometry and differential thermal analysis. The results show that the reaction involves many transitional stages, including formation of TiAl3 and transformation into TiAl and Ti3Al. The examination show that the composite materials fabricated by this in-situ crystallization from amorphization have good mechanical properties due to fine grain size and uniform microstructure.
Key words: titanium aluminide; Ti2AlN, composites; high energy milling; hot press sintering