Fe与BN反应形成Fe-N和Fe-B合金的热力学和动力学

Thermodynamic and Kinetic Mechanism of Formation of Fe-N and Fe-B Alloy in the Solid-state Reaction Process between Iron and Boron Nitride

利用机械球磨,常压和高压热处理技术对Fe与六方氮化硼(h-BN)(Fe与h-BN的体积比为1∶12.5)的固态反应过程和产物进行了研究.在常压,770和1170K条件下对球磨30h的Fe/BN样品热处理1h,结果表明在770K处理的样品中观察到少量γ′-Fe4N相,在1170K得到少量γ-Fe(N)相.利用机械球磨和高压热处理(4GPa,690-800K)可使所有的Fe与BN中的N原子反应形成单一的ε-FexN相.然而,在整个实验中没有观察到任何Fe-B合金相形成.本文对Fe-N合金形成和相转变的过程以及压力对固态反应和反应产物的影响进行了讨论,并利用Miedema模型与热力学和动力学理论对在Fe与BN固态反应过程中只形成Fe-N不形成Fe-B合金的热力学和动力学机制进行了探讨.

Solid state reaction process and resulting products of Fe and hexagonal boron nitride (h-BN) were studied by ball milling the mixture of Fe and h-BN with Fe to h-BN volume ratio of 1∶12.5 and/or heat treating it under normal or high pressure. The 30h-milled Fe/BN mixture was annealed for 1h under an atmospheric pressure at 770 and 1170K, respectively. It was found that a small amount of γ′-Fe_4N was observed in the mixture annealed at 770K and a few γ′-Fe_4N was obtained at 1170K. All Fe atoms reacted with N atoms in the BN to form a single phase of ε-Fe_xN when the mixture was milled for 60h or annealed for 1h under 4GPa at temperatures of 690-800K.However, no Fe-B phase was observed in the present experiment. Formation and phase transition of Fe-N alloy in the solid state reaction process as well as effect of pressure on the reaction and resulting products are discussed in the present paper. The mechanism of formation of Fe-N and Fe-B in the reaction process between Fe and BN are also investigated on use of Miedema model and thermodynamics and kinetics.