Cr对Fe-Cr合金耐蚀性能影响的电子理论研究  

Electronic Theoretical Study of the Influence of Cr on Corrosion Resistance of Fe-Cr Alloy

作　　者：王垚[1] 李春福[1] 林元华[1,2] 

机构地区：[1]西南石油大学材料科学与工程学院,成都610500 [2]西南石油大学油气藏地质及开发工程国家重点实验室,成都610500

出　　处：《金属学报》2017年第5期622-630,共9页Acta Metallurgica Sinica

基　　金：国家高技术研究发展计划项目No.2006AA06A105;西南石油大学油气藏地质及开发工程国家重点实验室基金项目No.PLN0609~~

摘　　要：基于固体与分子经验电子理论(EET),对Fe-Cr合金(Cr含量为0~30%,原子分数)的价电子结构进行了半定量分析,利用界面电子密度差Dr的计算方法,计算了Fe-Cr合金与Cr_2O_3、Fe_2O_3钝化膜低指数晶面间的电子密度。结果表明,Fe-Cr合金固溶体的杂化原子轨道数sn、最强键共价电子数nA和最强键键能EA均大于纯Fe,Cr能提高Fe基体的稳定性。当Cr含量达到12.52%和24.3%时,Cr原子从低阶迁移到共价电子数少的高阶状态,不稳定性增加,此时Cr易偏离平衡位置与腐蚀介质作用形成钝化膜,造成Fe-12.52%Cr和Fe-24.3%Cr合金的耐腐蚀性能发生突变。Fe-Cr合金与Cr_2O_3、Fe_2O_3钝化膜的24个低指数界面中,只有Fe-Cr(112)/Cr_2O_3(0001)、Fe-Cr(112)/Cr_2O_3(1010)_(Cr)、Fe-Cr(112)/Fe_2O_3(11 20)界面的Dr<10%,对于同等Cr含量的基体,Fe-Cr(112)/Cr_2O_3(1010)_(Cr)界面Dr最小,满足Dr<10%的杂化原子轨道数s最大。随着基体中Cr含量升高,Fe-Cr(112)/Cr_2O_3(0001)和Fe-Cr(112)/Fe_2O_3(11 2ˉ0)界面Dr降低,s增加,Cr_2O_3、Fe_2O_3与基体的界面更加稳定牢固,因此Fe-24.3%Cr合金的耐腐蚀性可跃迁至更高水平。价电子结构对Fe-Cr合金耐蚀性能变化的分析结果基本符合Tammann定律的描述。Based on the empirical electron theory （EET） of solids and molecules, the valence electron structure caculation results of Fe-Cr alloy containing （0~30%）Cr were analyzed semi-quantitatively. The electron density differences of interface （Δρ） between Fe-Cr alloy and Cr2O3, Fe2O3 passivation films were calculated. According to the results, adding Cr to α-Fe matrix can strengthen the matrix by improving the number of hybid atomic orbitals σn, the number of the strongest bond covalent electron pairs nA and the strongest covalent bond energy EA of Fe-Cr alloy. Once the content of Cr rises up to 12.52% and 24.3%, the corrosion resistance of Fe-Cr alloy is improved because of Cr being changed to a higher hybrid level, where Cr becomes more unstable and easily reacts with environment to form a complete passivation layer of Cr2O3. Moreover, among the electronic density differences of 24 low-index faces between Fe-Cr and Cr2O3, Fe2O3, only the Δρ of Fe-Cr（112）/ Cr2O3（0001）, Fe-Cr（112）/Cr2O3 （101？0）Cr,Fe-Cr（112）/Fe2O3（112？0） are lower than 10%. For the matrix with same content of Cr, the Δρ between Fe-Cr（112） and Cr2O3（101？0）Cr is the lowest, but the number of hybid atomic orbitals σ satisfied Δρ〈10% is the largest. Δρ （σ） of Fe-Cr（112）/Cr2O3（0001） and Fe-Cr（112）/Fe2O3（112？0） is decreased （increased） with the increase of Cr, therefore the interface bonding strength between Cr2O3, Fe2O3 and matrix will be enhanced, it has been found that the corrosion resistance of Fe-24.3%Cr is better. The calculation results of variation of Fe-Cr corrosion resistance with Cr content are in better agreement with Tammann＇s law.

关 键 词：经验电子理论 耐腐蚀性能 钝化膜 界面电子密度差 Tammann定律 

分 类 号：TG171[金属学及工艺—金属表面处理]