Analysis On Valence Electronic Structures Of Al-Ag Alloy And Its Effects On Properties Of Alloy

Al-Ag alloy is the representation of the aging hardening alloy, from the study of the microcosmic mechanism, we can find the rule which would be beneficial to the design for other alloy.The valence electron structures of main phases and phase interphase boundaries in Al-Ag binary alloy were analyzed according to the Empirical Electronic Theory in solid and molecules (EET). The following aspects are included in this thesis:1. The models of valence electron structure of main phases in Al-Ag binary alloy were established. The solid solution of Al-Ag binary alloy was contained two cells: a -Al cell, Al-Ag cell. The valence electron structures of above cells were calculated.2. The valence electron structures of the precipitations of Al-Ag binary alloy in early aging, such as phase of GP and r'(Ag2Al) and r(Ag2Al) were calculated.3. The valence interface energy of phase interphase boundaries between the matrix and the phase of G.P zone were calculated.4.The formation of PFZ around the r(Ag2Al) phase are interpreted according to the valence electron structures.5. The valence electron structures of phase interface boundary between the matrix and the precipitation are calculated.The results show that:The strong interaction of Al with Ag in solid solution of Al-Ag binary alloy, which lead to the behavior of Al-Ag segregation.The strongest bond in supersaturation solid solution of alloy is lower than the one in the matrix contribute to the low heat stability which lead to the decompose, accordingly the new phase segregate from the supersaturation solid solution.The bond net of the strongest and the hypobond in the cell of r(Ag2Al) which formed in the aging process, are so strong that the dislocation is difficult to cut, so the strength is improved.The interphase energy between the a-Al(111) and the phase(0001) of G.P zone is small, which account for the reason why the interface matched so well that the interface is more stable.a -Al( 111) and y (Ag2 Al) ( 0001) match well, the surface energy of the precipitates r(Ag2Al) (0001) is higher than the one of a-Al(111),which lead to the adsorption of the precipitates is stronger than the one of matrix, therefore, the precipitates free zones are formed around the precipitate r(Ag2Al) phase.On the interphase boundaries between the matrix and the precipitate y' (Ag2Al) (0001) , electronic density is continued in Al-Ag binary alloy. The functions of aging hardening are remarkable in the alloy.