Effect of Nb Content on Phase Evolutions and Microstructure of TiAl/Al2O3 Nano-composite Prepared by Mechano-thermal Processing
In this research,a composite structure composed of an ultra-fine grained TiAl intermetallic matrix together with dispersed nano-crystalline A12O3 particles was prepared by milling of TiO2 -Al powder mixture and its subsequent heat treatment. Various amounts of Nb powder were added to the reactants to investigate its effect on the whole process. Powder mixtures were subjected to severe mecharical activation using a planetary ball mill for 8 hours and the milled samples were cold pressed and heat treated at 500-700℃ to complete the solid state reactions. Structural changes and thermal behavior of the samples were evaluated by X-ray diffraction (XRD) and differential thermal analysis (DTA), respectively. Also, the microstructure of the composite was studied by scanning electron microscope (SEM). XRD results confirmed the partial dissolution of Nb in Al during the milling stage. It was observed that small amounts of Nb accelerate the aluminothermic reduction of TiO2 during heat treatment whereas; high Nb additions retard the reaction. Also, high Nb additions promote formation of Ti3Al phase during the heat treatment. Finally, it was shown that Nb addition changes the composite structure as increased Nb contents drastically refine the microstructure.
Titanium aluminide solid state reactions ultra-fine grain intermetallic matrix composite mechanical alloying
Saeed Heshmati-Manesh Somaye Alamolhoda Abolghasem Ataie
School of Metallurgy and Materials Engineering ,University of Tehran, Tehran,P. O. Box 14395-553, Iran
国际会议
The 12th World Conference Titanium(第十二届世界钛会 Ti-2011)
北京
英文
1411-1415
2011-06-19（万方平台首次上网日期，不代表论文的发表时间）