| In this paper,based on Yu's empirical electron theory of solid and molecule,i.e.EET and Cheng's improved TFD theory,the conception and the calculation methods of plane valence electron structure is defined and established,and the mathematic expression of relative electron density differenceâ–³Ïof phase interface is proposed.These lay foundation for the continuous calculation and application of electron density of phase interface.For the definite state of atoms in alloy if exiting biphase interface and arranging by definite phase relationship,the values of bond length difference(BLD)â–³D andâ–³Ïshould be both considered.The effect of two factors is considered simultaneously and atom state ascertainment factor w applied to study on the hybridization state of Fe atom in Fe-C austenite and Fe-C martensite and the hybridization state of atoms of Fe-C-Me unit cell in alloyed austenite is presented.The results indicate that in Fe-C austenite C-contained structure unit,the hybrid levels of Fec and Fef atoms are B13 and B14,respectively and in Fe-C martensite C-contained structure unit,the hybrid levels of Feâ… ,Feâ…¡and Feâ…¢atoms are A12,A10 and A9,respectively.For alloyed austenite,different Me(any alloying elements)atoms make the hybridization states of Fec and Fef atoms change accordingly. The hybridization states of Fec,Fef and Cr atoms in Fe-C-Cr unit cell are B14,B15 and A7(or A8),respectively;those of Fec,Fef and W atoms in Fe-C-W unit cell are B13,B14 and C1(or C2),respectively;those of Fec,Fef and Si atoms in Fe-C-Si unit cell are B15, B16(or B17)and A1(A2 or A3),respectively;those of Fec,Fef and Mn atoms in Fe-C-Mn unit cell are B14(or B13),B15 and C11,respectively,w is applied to ascertain the hybridization states of atoms of alloying elements,which made that the electron density of the contacting surface between atoms must be continuous(the boundary condition of the movement of electrons)by Cheng Kaijia applied to the calculation of Yu's theory,which can not only simplify the multiply solution ascertaining the hybridization states of atoms, but also join Yu's theory and Cheng's theory at the bonding point that biphase interface electron density is continuous.Valence electron structures of some metals of A1,A2 and A3 model crystal structures are respectively calculated and the analytic general formula of plane valence electron structure of three models metal is presented.A new parameter "F" is taken as the difficulty coefficient of slipping along certain face.The smaller the value of F is,the easier the slipping;on the contrary,the slipping is much more difficult.In A1,A2 and A3 model crystal structures,the F values of many other crystal planes are calculated and the results show that the crystal planes with the minimum F are {111},{110} and {0001} respectively.So in the level of valence electron structure,the reason that {111},{110} and {0001} are respective slip plane of A1,A2 and A3 model can be explained.By applying the boundary condition of the movement of electrons in Cheng's improved TFD theory to Yu's theory,electron density of a few low index crystal face that the atoms arrange more dense in Fe-C austenite and Fe-C martensite is calculated.The calculate data are analyzed and the definite orientation relationship of martensite phase transformation is discussed in the level of valence electron structure.When austenite transformed to martensite,relative electron density difference between the plane of(111) of austenite and the plane of(110)of martensite is 6.95%,which is smaller than 10%,i.e. the plane of(111)of austenite and the plane of(110)of martensite is continuous under the first-order approximation.According to the quantum-mechanical condition that the boundary condition between atoms is only that the electron density must be continuous in solid presented in Cheng's theory,the definite orientation relationship is(111)γ//(110)αwhen austenite transforms to martensite,.The effect of alloying elements on the phase transformation point Ms of austenite is studied according to bond energy.The calculation shows that the maximum value of covalent bond energy of alloyed austenite unit cell is bigger than the one of Fe-C unit cell when the Mo,Cr,W,Mn,Ni etc.alloying elements melt into the austenite.So it needs more energy to break the most powerful bond of alloying austenite unit cell for the sake of the transformation from austenite to martensite,i.e.the alloying elements have affected the transformation temperature from austenite to martensite.The more the value of covalent bond energy is increased,the larger degree of supercooling is needed and the lower the phase transformation tempreture is.The rule that Ms from austenite to martensite is affected by Mn,Cr,Ni,Mo,W etc.alloying elements is that the function of Mn,Cr,Ni decreasing the Ms is stronger,while Mo and W take second place,which is in accord with the experimental rule in metallurgy.Based on the thought of average cell model and average atom model,the detailed calculation methods of valence electron structure of Fe-interstitial solid-solution and substitution solid-solution and Al-Mg substitution solid-solution are presented,respectively. Inγ-Fe-C solid-solution,the number of covalent electron pairs nA of the most powerful bond of C-contained unit cell is increased about 2 times than the one of matrix(γ-Fe);the nA ofγ-Fe-N solid-solution N-contained unit cell is increased about 1.4 times than the one of matrix(γ-Fe).In substitution solid-solution,however,the nA of Al-Mg solid-solution Mg-contained unit cell,the one of Fe-Si solid-solution Si-contained unit cell and the one of Fe-Mn solid-solution Mn-contained unit cell are almost accord with the one of matrix.The reason interstitial solid-solution strengthening is stronger than substitution solid-solution's obviously is the variation of nA.So the mechanism of solid-solution strengthening can be presented using the valence electron structures of the solid-solution.
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