摘要
借助X射线衍射和透射电子显微镜研究了在机械驱动下难熔金属Ta与N2 的氮化反应 .实验发现 ,在室温下的高能球磨可实现Ta N2 反应 ,并形成三种不同结构的氮化物 :六方结构的Ta2 N ,四方结构的Ta3 N5和非晶相 .研究表明 ,N2 在清洁的金属表面上发生可离解式的化学吸附是Ta N2 反应的基本过程 ,高的Ta—N键合能是N2 分子在Ta表面上发生化学吸附的热力学驱动力 ,而球磨在金属粉末中引入的储能 (界面能和缺陷能 )为Ta—N向金属氮化物转变提供了激活能 .球磨后期非晶相的形成则源于Fe的侵入 ,所形成的非晶相含有Ta Fe N三种元素 .
The nitriding reactions between tantalum and molecular nitrogen activated by mechanical milling are investigated by X-ray diffraction and transmission electron microscopy. It is found that the high-energy milling at ambient temperature can activate Ta/N 2 reaction and causes the formation of three different structures, including tetragonal Ta 2N, hexagonal Ta 3N 5 and an amorphous phase. The chemisorption of nitrogen onto the clean tantalum surfaces created by milling is the dominated processes governing Ta/N 2 reaction. The binding energy of Ta—N band much higher than that of N—N band provides the thermodynamic driven force for N 2 decomposition, while the energy input due to introduction of high density of grain-boundaries and lattice defects offers the activation energy for the transition from Ta—N bands to Ta-nitrides. The amorphous phase formed in the later stage of milling is caused by iron intake due to the contamination from milling tool. The results demonstrate that the amorphous phase obtained consists of three elements of Ta, Fe and N.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2002年第3期603-608,共6页
Acta Physica Sinica
基金
国家自然科学基金 (批准号 :5 99710 2 0 )资助的课题~~
