利用经验电子理论(EET)分析Al对Fe-Cr高温合金冲击韧性的影响

An Analysis on Effect of Al on Impact Toughness of Fe-Cr High Temperature Alloy by Empirical Electron Theory(EET)

采用Thermal calc热力学软件,计算了新型含铝Fe-Cr合金(/%:1.60C、26.00Cr、5.50Al、0.50Ni、0.12Y)的相图,结合X射线衍射分析,确定了该合金的相组成。在此基础上,运用固体与分子经验电子理论(EET),分析了普通高铬铸铁和含铝Fe-Cr合金的价电子结构、共价键键能以及晶格电子数,从电子层面揭示含铝Fe-Cr合金冲击韧性下降的微观机理。结果表明,添加5.50%Al后,Fe-Cr合金中出现了含铝结构单元,这些单元中最强键共价电子对数从0.48640降低为0.450 31,次强键共价电子对数也从0.199 83降低到0.118 88,同时晶格电子数有所减少,从而导致其冲击韧性下降。含5.50%Al的Fe-Cr高温合金冲击韧性的EET预测结果与实测结果吻合良好。

The phase diagram of a new aluminium-bearing Fe-Cr alloy （/% ： 1.60C, 26. 00Cr, 5.50A1, 0. 50Ni, 0. 12Y） is calculated by using thermodynamics software Thermal talc, and combined with X-ray diffraction analysis the phase composition of the new alloy is defined. On this basis, the valence electron structure, covalent bond energy and lattice electrons of conventional high chromium cast iron and aluminum-bearing Fe-Cr alloys are analyzed by using solid and molecule empirical electron theory （EET） to reveal the mechanism for impact toughness decreasing of aluminum-bearing Fe-Cr alloy at electronic level. Results show that with adding 5.50% A1, the aluminum-bearing structure units occur in FeCr alloy, the strongest bond covalent electron pairs in the units decrease from 0. 486 40 to 0. 450 31, second strong bond covalent electron pairs also decrease from 0. 199 83 to 0.118 88, while the number of lattice electrons decreases led to the impact toughness lowing. The EET predicting results for impact toughness of Fe-Cr alloy containing 5.50% A1 nicely coincide with the test measured results.