Study on the Stability and Phase Transition of Precipitated Phases Al6Fe and Al3Fe in Al-Fe Alloy

2011 ◽  
Vol 306-307 ◽  
pp. 438-442
Author(s):  
Hua Qu ◽  
Wei Dong Liu
Keyword(s):  
Phase Transition ◽  
Valence Electron ◽  
Electron Theory ◽  
Electron Pairs ◽  
Empirical Electron Theory ◽  
Equilibrium Solidification ◽  
The Stability ◽  
State Group ◽  
Precipitated Phases ◽  
Strengthening Phases

Based on the empirical electron theory of solids and molecules theory(EET), the valence electron structures(VESs) of the strengthening phases Al3Fe and Al6Fe in Al-Fe alloy are calculated, then the stability of Al3Fe and Al6Fe, the precipitated sequence under the non-equilibrium solidification, the phase transition during aging and the effects of alloy elements are discussed. The results show that the values of covalent electron pairs on the strongest bondn1, the total forming bond abilityF, and the number of atom state groupσNof Al3Fe and Al6Fe are bigger than that of Mg17Al12 and Mg2Si, so the stability of Al3Fe and Al6Fe is better. The total forming bond ability of Al6Fe is far smaller than that of Al3Fe, so Al6Fe generates first under the equilibrium solidification. The strongest bond of Al6Fe is weaker than that of Al3Fe, so Al6Fe is easy to be broken up and form the more stable Al3Fe finally during aging. The addition of alloy elements changes the VES of Al6Fe and makes its values ofF,σNandn1increased, the stability of Al6Fe is strengthened too, which delays the Al6Fe→Al3Fe transition and improves the transition temperature.

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.

Relationships between the Abilities of the Forming Bond of the Precipitated Phases and their Precipitations and Phases Transition in Al-Fe-Si Alloy

2010 ◽  
Vol 152-153 ◽  
pp. 1049-1053
Author(s):  
Hua Qu ◽  
Wei Dong Liu ◽  
Chuang Liu ◽  
Gang Zhou ◽  
Xiao Lu Shen
Keyword(s):  
High Temperature ◽  
Solid Solutions ◽  
Electron Theory ◽  
Empirical Electron Theory ◽  
The Matrix ◽  
Cooling Speed ◽  
The Stability ◽  
Precipitated Phases

According to the empirical electron theory of solid and molecule, the valence election structures of the matrix  of Al-Fe-Si alloy, solid solutions of -Al-Fe and -Al-Fe-Si, precipitated phases of A13(Fe,Si), Al8Fe2Si and Al12Fe3Si and their abilities of the forming bond were calculated, then the relationships between the abilities of the forming bond of the main precipitated phases in Al-Fe-Si alloys and their precipitations and phases transition were studied in this paper. From the results we find that the ability of the forming bond of Al12Fe3Si (637.23) is small, that of Al3(Fe,Si) (670.52) is large and that of Al8Fe2Si (1038.27) is the largest; the larger the cooling speed, the more amount of the precipitated first of Al12Fe3Si, the few amount of the precipitated of Al3(Fe,Si) and Al8Fe2Si; the stability of Al12Fe3Si is smaller than that of Al3(Fe,Si) and Al8Fe2Si, and under high temperature, the phase of Al12Fe3Si can grow up and coarsen and even change into Al3(Fe,Si) and Al8Fe2Si.

Study on the Precipitated Behavior and Stability of the Strengthening Phase Al12(Fe,X)3Si in Al-Fe-Si-X Alloys with the EET Theory

2010 ◽  
Vol 152-153 ◽  
pp. 743-747
Author(s):  
Hua Qu ◽  
Wei Dong Liu ◽  
Gang Zhou ◽  
Xiao Lu Shen ◽  
Chuang Liu
Keyword(s):  
Valence Electron ◽  
Electron Structure ◽  
Alloying Elements ◽  
Strengthening Phase ◽  
Alloying Element ◽  
Valence Electron Structure ◽  
Empirical Electron Theory ◽  
Calculation Results ◽  
The Stability ◽  
State Group

According to the empirical electron theory of solid and molecule, the effects of alloying elements on the valence electron structure, precipitated behavior and stability of Al12Fe3Si were studied in this paper. The calculation results show that the adding of V, Cr, W, Mo and Mn change the valence electron structure of Al12Fe3Si, and make its number of atom state group N increased by 2 orders of magnitude, so it make the stability of the alloy increased and then delay the coarsening speed; the adding of alloying element makes the total ability of forming bond F reduced and accelerates the precipitated of Al12Fe3Si and make it refined; the order for the adding of the alloying elements V, Cr, W, Mo and Mn of the effects on stability of Al12Fe3Si is Cr(Mn)→W(Mo)→V, and that of accelerating the dispersion precipitated of Al12Fe3Si is Cr→V→Mo→W→Mn; when practicing to design Al-Fe-Si-X alloy, we can obtain it through controlling the ratio of Fe/X to refine the particles of Al12(Fe,X)3Si, therefore, its stability can be improved and its coarsening can be delayed.

Calculation of Valence Electron Structure of Precipitate Phases in Al-Cu Cast Alloy

2011 ◽  
Vol 311-313 ◽  
pp. 758-763
Author(s):  
Chang Tian ◽  
Rui Chun Wang ◽  
Run Xia Li ◽  
Rong De Li
Keyword(s):  
Valence Electron ◽  
Cast Alloy ◽  
Electron Structure ◽  
Electron Theory ◽  
Valence Electron Structure ◽  
Electron Pairs ◽  
Length Difference ◽  
Empirical Electron Theory ◽  
Structure Factors ◽  
Thermal Stability Of

Based on Empirical Electron Theory in solid (EET) and Bond Length Difference (BLD) the valence electron structures of precipitates in AlCu alloy during aging process were calculated. The results show that the different phase structure factors explain the thermal stability of phases in θ sequence, and the tendency of atoms solution is corresponding with the phase transition during aging from valence electron structure levels, which reveals the inside causes of ageing hardening is closely related to the covalent electron pairs in some bond of the precipitations and matrix.

Theoretical Calculation of β Transition Temperature of Ti-6Al-4V from Valence Electron Level

2011 ◽  
Vol 299-300 ◽  
pp. 592-595
Author(s):  
Hua Qu ◽  
Wei Dong Liu
Keyword(s):  
Transition Temperature ◽  
Theoretical Calculation ◽  
Titanium Alloys ◽  
Valence Electron ◽  
Electron Theory ◽  
Electron Level ◽  
Valence Electron Structure ◽  
Electron Pairs ◽  
Stable Element ◽  
Empirical Electron Theory

Based on the empirical electron theory of solids and molecules and the basic theory of the phase transformation of titanium alloys, a new method to calculate β transition temperature of titanium alloys is put forward after calculating the valence electron structure(VES) parameternAwhich is the covalence electron pairs on the strongest bond of alloy phases, the crystal cell weight of a and b phases in the structure, the compensation coefficient of the phase and the temperature coefficient of b stable element. After calculating we find β transition temperature of Ti-6Al-4V is 974.9 °C, the error of the theoretical calculation value and the experimental one(995 °C) is 2%, so it is feasible to calculate β transition temperature of the titanium alloys from covalence electron level.

Analysis of the Valence Electron Structures of the Strengthening Phases Al8Fe4Ce and Al4Ce in Al-Fe-Ce Alloy

2011 ◽  
Vol 194-196 ◽  
pp. 1291-1295 ◽  
Author(s):  
Hua Qu ◽  
Wei Dong Liu ◽  
Yu Ying Liu
Keyword(s):  
Network Structure ◽  
Valence Electron ◽  
Grain Refining ◽  
Electron Theory ◽  
The Third ◽  
Empirical Electron Theory ◽  
Atom Group ◽  
The Matrix ◽  
Bond Network ◽  
Strengthening Phases

Based on the empirical electron theory of solids and molecules (EET), the valence electron structures (VESs) of the strengthening phases Al8Fe4Ce and Al4Ce in Al-Fe-Ce alloy were calculated, then the relationships between the VESs and strengthening, stability of the alloy and grain refining were analyzed. The results show that the distribution of the bond network of Al8Fe4Ce is uniform, the third and the fourth bonds in the bond network of Al4Ce is the weakest segment of the whole bond network structure, and the strongest bond in the bond network of Al8Fe4Ce and Al4Ce is stronger than that of the matrix of the alloy. The VES of Al8Fe4Ce is favourable to stability of the alloy. During solidifying of the alloy, because the bonds formed by Ce atom and its adjacent atoms are all strong, that hinders Al atoms adjacent to Ce atom to involve in the growth of other grains and at the same time hinders the growth of the Ce atom group, so the structure of the alloy can be refined.

Calculation and Analysis of Valence Electron Structures of the Precipitated Phases in Al-Cu Alloy

2009 ◽  
Vol 79-82 ◽  
pp. 1177-1180
Author(s):  
Wei Dong Liu ◽  
Hua Qu
Keyword(s):  
Bond Strength ◽  
Valence Electron ◽  
Strengthening Effect ◽  
Electron Pairs ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Empirical Electron Theory ◽  
The Matrix ◽  
Dislocation Movement ◽  
Precipitated Phases

According to the empirical electron theory of solids and molecules, the valence electron structures of GP zone, θ″, θ′ and θ phases in Al-Cu alloys are calculated out. The results show that the number of covalent electron pairs on the strongest bond A of GP zone is greater than that of of the  matrix, i.e., the obstruction of in GP zone for dislocation movement is stronger than that of in the  matrix. Only based on the bond strength of composition atoms, it can be found, , , and  phases have strengthening effects for Al-Cu alloys. The strengthening effect of  is the strongest, and  is weaker, and  is the weakest. Compared with, the bond strength of  and  is weaker than that of . From the value of nA, it is easy to reconstruct the bonds of GP zone, , and , but is difficult to reconstruct the bonds of .

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.

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