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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 of solids and molecules (EET), the valence electron structures of Fe-Cr alloys (Cr content from 0 to 30%, atomic fraction) were semi-quantitatively analyzed. Using the calculation method of interfacial electron density difference Dr, Electron Density Between Low Index Crystal Surfaces of Fe-Cr Alloy and Cr_2O_3 and Fe_2O_3 Passivation Films. The results show that the number of hybrid orbital sn, the number of the strongest bond covalent electron nA and the maximum bond energy EA of Fe-Cr alloy solid solution are larger than that of pure Fe and Cr, which can improve the stability of Fe matrix. When the Cr content reaches 12.52% and 24.3%, the Cr atoms migrate from the lower order to higher order states with fewer covalent electrons, and the instability increases. At this time, Cr easily deviates from the equilibrium position to form a passivation film with the corrosive medium, resulting in The corrosion resistance of Fe-12.52% Cr and Fe-24.3% Cr alloys is abrupt. Among the 24 low-index interfaces between Fe-Cr alloy and Cr 2 O 3 and Fe 2 O 3 passivation films, only Fe-Cr (112) / Cr 2 O 3 (0001), Fe-Cr 112 / Cr 2 O 3 1010 Cr, For the same Cr content matrix, the interface of Fe-Cr (112) / Cr_2O_3 (1010) Cr is the smallest, which satisfies Dr <10% The number of atomic orbital s largest. With the increase of Cr content in the matrix, the interface Dr of Fe-Cr (112) / Cr_2O_3 (0001) and Fe-Cr (112) / Fe_2O_3 (11 2ˉ0) decreases and s increases and the interface between Cr_2O_3 and Fe_2O_3 is more stable and stable , So the corrosion resistance of Fe-24.3% Cr alloy can jump to a higher level. The analysis results of the valence electron structure on the corrosion resistance of Fe-Cr alloy are basically in accordance with the description of Tammann’s law.