氢在钢中晶格间隙和氢陷阱之间的扩散模式

Hydrogen diffusion Models between Lattice Interstitial Sites and Hydrogen Trapping Sites in the Steel

氢在晶格间隙和陷阱点的扩散包括:氢在晶格间隙之间的扩散,氢从晶格间隙扩散到陷阱点,氢从陷阱点逃逸到晶格间隙的过程。本文运用气体在金属中的扩散理论,分析了氢在钢中晶格间隙和氢陷阱之间的扩散模式,以及通过扩散在两者之间建立的平衡状态。氢陷阱中氢浓度随时间的变化率等于晶格间隙的氢扩散到陷阱点引起的氢浓度变化率减去陷阱点中氢逃逸到晶格间隙引起的氢浓度变化率,其数学关系式符合McNabb和Foster建立的氢陷阱模型。氢在晶格间隙和陷阱点之间的平衡,实质是氢在晶格间隙的化学势μL和氢在陷阱点的化学势μT之间达到局部平衡,氢在陷阱中的占据分数很低的情况下(θT《1),氢的有效扩散系数Deff的表达式是与陷阱结合能EB有关的温度函数。

Various hydrogen trapping sites exist in the steel which can dissolve the hydrogen and decrease the diffusing hydrogen. To investigate the effect of trapping sites on the hydrogen distribution, hydrogen diffusion models and the equilibrium states between the lattice interstitial sites and the hydrogen trapping sites were analyzed by using the theory of gas diffusing in the metal. Hydrogen concentration changing rate with respect to time is equate to the changing rate of hydrogen diffusing from lattice interstitial sites to trapping sites subtract the changing rate of hydrogen desorption from trapping sites to lattice interstitial sites, and the mathematic equation is agreed with McNabb and Foster＇s hydrogen trapping models. There is local hydrogen equilibrium between the lattice interstitial sites and trapping sites. When the hydrogen occupancy of trapping sites is very low（θT《1） ,hydrogen effective diffusion coefficient（Deff） is function of temperature（T） with respect to trapping energy（EB ）.