One-step mechanosynthesis of nano structured Ti(CxN1鈭?/sub>x) cermets at room temperature and their microstructure characterization
- 作者：Ujjwal Kumar Bhaskara ; S.K. Pradhanb ; skp_bu@yahoo.com
- 关键词：Mechanical alloying ; Nanostructures ; Nitrides ; Electron microscopy ; X-ray diffraction
- 刊名：Materials Chemistry and Physics
- 出版年：2012
- 期刊代码：58_02540584
- 类别：ms
- 出版时间：15 June, 2012
- 卷：134
- 期：2-3
- 页码：1088-1096
- 文件大小：1669 K
摘要
Nano structured Ti(Cx,N1鈭?/sub>x) (x聽=聽0.1-0.5聽mol fraction) cermets are prepared at room temperature in a single step by ball-milling the stoichiometric mixtures of elemental 伪-Ti and graphite powders under nitrogen atmosphere. Within 1聽h of milling (for x聽=聽0.1), the 伪-Ti (hcp) phase partially transformed to metastable 尾-Ti (cubic) phase and the initiation of Ti(Cx,N1-x) (fcc) phase is noticed. Complete formation of Ti(C0.1N0.9) composition is observed after 5聽h of milling and the other compositions are formed within 7聽h of milling without any contamination either from the starting ingredients or from the milling media. Microstructure characterization of all unmilled and ball-milled powders is made by analyzing their respective X-ray diffraction (XRD) patterns employing the Rietveld structure refinement method. The microstructure of ball-milled samples is also characterized by high resolution transmission electron microscope (HRTEM). These analyses reveal the inclusion of both C and N atoms into the 伪-Ti lattice and confirm the average particle size of almost monodispersed spherical particles of Ti(Cx,N1-x) is 鈭?聽nm. The final compositions are also verified by energy dispersive X-ray (EDX) elemental analysis. Ti(Cx,N1-x) cermets are insulators and their optical band gap increases continuously from 鈭?.58-5.38聽eV with increasing C concentrations.