Effects of Mo(Ni) on Valence Electron Structures of TiC/Fe Cermets

2008 ◽  
Vol 368-372 ◽  
pp. 1119-1122 ◽  
Author(s):  
Zheng Guang Zou ◽  
Yi Wu ◽  
Fei Long ◽  
Wen Wu Xu ◽  
Dong Ye Yao
Keyword(s):  
Binding Energy ◽  
Electron Density ◽  
Valence Electron ◽  
Electron Cloud ◽  
Metal Phase ◽  
Structure Model ◽  
Electron Theory ◽  
Ceramic Phase ◽  
Empirical Electron Theory

Based on the empirical electron theory (EET) of solids and molecules, the valence electron structures (VESs) of TiC-Mo(Ni)-Fe system were calculated by building proper structure model. The results indicate that additives of Mo and Ni improve the interface conjunction factors of the cermets in different ways. By adding Mo, the VESs of the ceramic phase are improved for the formation of the rim phase (Ti1-xMox)C, which leads to the enhancement of the interface conjunction, while the improvement of the VESs on metal phase by adding Ni is due to the formation of the Fe100-yNiy. Mo and Ni additives increase the interface electron density of cermets, that is, the adding of the Mo and Ni enhance the overlapping grade of the electron cloud on interface and increase the binding energy of the interface, which is propitious to the wettability. The best wettability was found at x=0.5 or y=30.

Analysis of Valence Electron Theory on the Catalytic Mechanism of Diamond Single Crystal Growth

2007 ◽  
Vol 353-358 ◽  
pp. 2998-3001 ◽  
Author(s):  
Li Li ◽  
Bin Xu ◽  
Mu Sen Li ◽  
Jian Hong Gong
Keyword(s):  
Electron Density ◽  
Valence Electron ◽  
Catalytic Mechanism ◽  
Diamond Structure ◽  
Dirac Theory ◽  
Electron Theory ◽  
Valence Electron Structure ◽  
Large Numbers ◽  
Empirical Electron Theory ◽  
Structure Factors

Large numbers of experimental results show that carbides Me3C (Me means Fe, Ni, Co, Mn) are the primary carbon source to form diamond structure under the high temperature and high pressure (HPHT). In this paper, based on the empirical electron theory of solids and molecules (EET), the valence electron structure (VES) and interface structure factors of diamond and various carbides are calculated, and the boundary condition of electron movement in the improved Thomas- Fermi-Dirac theory by Cheng (TFDC) is applied to the carbide/diamond interfaces. It is found that the electron density of crystal plane in Me3C formed by C-C bonds is continuous with that in diamond at the first order of approximation. Compared with Ni-based carbides [Ni3C, (NiMn)3C)], the electron density difference of Fe-based carbides [Fe3C, (FeNi)3C, (FeMn)3C]/diamond interfaces is lower, and that of (FeNi)3C/diamond interface is minimum. The results show that the energy needed to transform carbon atomic groups into diamond structure is lower for Fe-based carbides than Ni-based carbides.

Theoretical Calculation of the Polytypism Transition Temperature of Titanium Alloys on the Valence Electron Level

2012 ◽  
Vol 152-154 ◽  
pp. 342-347
Author(s):  
Hua Qu ◽  
Wei Dong Liu
Keyword(s):  
Transition Temperature ◽  
Titanium Alloys ◽  
Valence Electron ◽  
Pure Titanium ◽  
Electron Theory ◽  
Electron Level ◽  
Valence Electron Structure ◽  
Electron Pairs ◽  
Stable Element ◽  
Empirical Electron Theory

Based on the polytypism transition temperature(PPT) of pure titanium, the the empirical electron theory of solids and molecules(EET) and the basic theory of the phase transformation of titanium alloys, a new method to calculate the PTT of titanium alloys is put forward after calculating the valence electron structure(VES) parameter nA which is the covalence electron pairs on the strongest bond of alloy phases, the crystal cell weight of  and  phases in the structure, the compensation coefficient of the phase and the temperature coefficient of  stable element. After calculating the PTT of some common titanium alloys, we find that the theoretical values are consistent with the experimental ones, so it is feasible to calculate the polytypism transition temperature of the titanium alloys on the covalence electron level.

Analysis of Structural Condition and Thermodynamics Condition of Graphite Heterogeneity Nucleation in Cast Iron

2011 ◽  
Vol 299-300 ◽  
pp. 576-579
Author(s):  
Hua Qu ◽  
Wei Dong Liu
Keyword(s):  
Crystal Structure ◽  
Cast Iron ◽  
Valence Electron ◽  
Large Angle ◽  
Structural Condition ◽  
Nucleation Theory ◽  
Electron Theory ◽  
Modern Times ◽  
Bond Forming ◽  
Empirical Electron Theory

Based on the empirical electron theory of solid and molecule, the valence electron structures(VESs) of graphite, CaS and MnS in cast iron are calculated, their bond-forming energy F of the structure unit and bond-forming energyEof the crystal plane are defined and calculated. Combined with the nucleation theory of the liquid metal,Fand E are applied to analyze the thermodynamics condition of graphite heterogeneity nucleation in undercooling liquid of case iron, i.e.,GL-FG>GL-FH,>. According to the coincidence lattice model of large-angle grain boundary used commonly in modern times, the corresponding structural condition is analyzed, i.e., the crystal structure of graphite should have the better lattice contract ratio with the crystal structure of its annexed heterogeneous particles.

The Valence Electron Structure of High-Entropy Alloys

2017 ◽  
Vol 1142 ◽  
pp. 3-7
Author(s):  
Bo Cheng ◽  
Yun Kai Li ◽  
Gui Qin Hou
Keyword(s):  
Valence Electron ◽  
Electron Pair ◽  
Electron Structure ◽  
High Entropy Alloys ◽  
Electron Theory ◽  
Valence Electron Structure ◽  
High Entropy ◽  
Melting Temperatures ◽  
Empirical Electron Theory ◽  
Pair Number

Empirical Electron Theory in Solids and Molecules (EET) was used to analyze the valence electron structure of ZrTiHfVNb, ZrTiHfVTa and ZrTiHfNbMo high-entropy alloys. The parameters characterizing the valence electron structure of high-entropy alloys were calculated, which were used to discuss the hardness and melting temperature of high-entropy alloys. The results show that the hardness of high-entropy alloys is positively correlated to the shared electron pair number in valence electron structure. The theoretical melting temperatures of high-entropy alloys were predicted by the parameters characterizing the valence electron structure.

Application on Statistical Value of Phase Structure Formation Factor to Fe-C Phase Diagram

2011 ◽  
Vol 299-300 ◽  
pp. 246-249
Author(s):  
Wei Hua Xue ◽  
Xin Ren ◽  
Zhi Yu Gao ◽  
Hai Fang Shi
Keyword(s):  
Phase Diagram ◽  
Structure Formation ◽  
Phase Structure ◽  
Valence Electron ◽  
Calculation Methods ◽  
Formation Factor ◽  
Electron Theory ◽  
Valence Electron Structure ◽  
Austenitic Phase ◽  
Empirical Electron Theory

Based on the empirical electron theory in solids and molecules (EET), the statistical value of phase structure formation factor (S') was calculated by using the calculation methods of statistical value of alloying valence electron structure parameters. The effects of alloying elements upon austenitic zone of Fe-C phase diagram were discussed. The results show that: 1) Mn and Ni can increase the S' value of γ-Fe and austenitic phase, which increase their stability, leading to expand the γ-zone; 2) Cr, Mo and Si can increase the S' value of ferrite and cementite, which make them easier to precipitate, leading to reduce γ-zone. The research results agree well with real situations.

Relationship between Valence Electron Structures and Mechanical Properties of ZL203

2012 ◽  
Vol 152-154 ◽  
pp. 336-341
Author(s):  
Hua Qu ◽  
Wei Dong Liu
Keyword(s):  
Mechanical Properties ◽  
Valence Electron ◽  
Strengthening Effect ◽  
Strengthening Phase ◽  
Electron Theory ◽  
Valence Electron Structure ◽  
Empirical Electron Theory ◽  
Dislocation Movement ◽  
Aging Stage ◽  
The Relationship

Based on the empirical electron theory of solids and molecules(EET) and valence electron theory of composition design of alloy, the valence electron structure(VES) of phases and phase interfaces of ZL203 are calculated in this paper, and the relationship between the VESs and mechanical properties are also studied. The results are as followed: 1) The of GP is bigger than of a, in other words, the resistance of dislocation movement in GP zone is bigger than that of in a matrix. 2) Compared with a matrix, the phases of q¢¢、q¢、q all have strengthening effects. From the bond combination of atoms composed in the strengthening phase of view, the strengthening effect of q is the best, that of q¢ is second, that of q¢¢ is the worst. 3) The precipitation sequence determined bynAis well accordance with that of depended on thermodynamics free energy. 4) The electron density difference Dr of a/GP, a/q" and a/q¢ interfaces increases one by one, and the stress of these interfaces also increases one by one, therefore the strength falls down one by one. 5) Combined with FSFs and ICFs, we can deduce that the best aging stage of ZL203 is the end of the precipitation of q¢¢ and the beginning of the precipitation of q¢.

ANALYSIS OF VALENCE ELECTRON STRUCTURE ONFe3AlCxPRECIPITATED FROM C-ALLOYED IRON ALUMINIDES

2013 ◽  
Vol 20 (01) ◽  
pp. 1350005 ◽  
Author(s):  
XIAO-FENG TIAN ◽  
WEI-KE ZHANG ◽  
YU QI
Keyword(s):  
Valence Electron ◽  
Theoretical Explanation ◽  
Electron Structure ◽  
Iron Aluminides ◽  
Electron Theory ◽  
Valence Electron Structure ◽  
Alloyed Iron ◽  
Empirical Electron Theory ◽  
The Matrix ◽  
Brittle Phase

Carbides of Fe3AlCxprecipitated from iron aluminides can strengthen the matrix; the empirical electron theory (EET) was applied to analyze the attribute of carbides in the paper, giving theoretical explanation on the matrix and precipitation. Valence electron structure (VES) of Fe3AlCxwas studied in detail, comparison with the iron aluminides matrix, the hard and brittle phase of Fe3AlCxcan be interpreted form the viewpoint of valence electron structure.

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