【作者】 韩永剑；

【导师】 高英俊；

【作者基本信息】 广西大学 ， 理论物理， 2004， 硕士

【摘要】 Al-Zn-Mg合金由于其低密度、高强度及较好的时效硬化效应，在航空航天工业中有着重要的应用。但该系合金对应力腐蚀断裂敏感，过时效处理在改善抗应力腐蚀断裂性能的同时却会致使强度降低。为了使经合理的热处理后的该合金既具有较好的应力腐蚀断裂性能，同时又能保持其强度，对合金结构与性能的微观机理的研究至关重要。然而，目前对Al-Zn-Mg合金的结构与性能的微观机理研究仍处于探索阶段。本文运用固体与分子经验电子理论(简称EET理论)，并结合程开甲院士改进的TFD方法，系统地研究了Al-Zn二元和Al-Zn-Mg三元合金中各固溶相和部分沉淀相的价电子结构及其界面性能，为该合金的进一步开发研究提供理论依据。主要研究内容如下： 1．建立Al-Zn系合金固溶体中存在各相的价电子结构模型，认为固溶体内包含了四类晶胞：α-Al晶胞，富Al的Al-Zn晶胞，富Zn的Al-Zn晶胞和Zn晶胞。运用平均原子模型计算了这些晶胞的价电子结构，并在价电子结构层次探讨该合金的Spinodal分解现象及合金组织的稳定性。 2．对Al-Zn系合金的过饱和固溶体在时效过程中脱溶的G．P．区，中间相和析出相的价电子结构进行计算，并对这些相对合金性能的影响进行了讨论。摘要 3.对Al一Zn一Mg系合金固溶体中可能的AI一Zn，AI一Mg及Mg一Zn二元偏聚晶胞和Al一Zn一Mg三元偏聚晶胞的价电子结构进行计算，分析了该合金中叮、粉析出相的结构模型。 4.对AI一Zn系合金过饱和固溶体在时效过程中脱溶的G.P.区与母相的界面能做了计算，并对其界面的面电荷密度进行计算。更多还原

【Abstract】 Al-Zn-Mg Alloys played an important role in the avigation and spaceflight due to their low density,high strength and preferable age hardness. -One drawback of these alloys was their susceptibility to stress corrosion cracking(SCC). Although overaging processes could improve the performance of resistance to stress corrosion cracking ,it could reduce the alloys’ strength simultaneously. The study of the microcosmic mechanism between structure and performances was of great importance in order to keep the alloys’ progressive stress corrosion cracking together with their high-strength after appropriate heat treatment. Unfortunately just very limited work has been done on studying the microcosmic mechanism between the structure and performances.The valence electron structures and interphase performances of each solid solution and part of the precipitations in Al-Zn and Al-Zn-Mg alloys were analyzed systematically according to the Empirical Electronic Theory in solid and molecules (EET) and improved TFD method by Cheng Kaijia.The research work made it possible for further study as theoretical basis.The main contents of this paper were as follows:Firstly,the models of valence electron structures of phases in Al-Zn based alloys were established. There were four kinds of cells in Al-Zn based alloys: a-Al cell; Al-Zn cell riching Al; Al-Zn cell riching Zn and Zn cell. The valence electron structures of above cells were calculated based on the average atom model.Then the Spinodal decompound phenomenon and the stability of morphology in Al-Zn alloy were discussed in the valence electron structure level. . -Secondly, the valence electron structures of G.P. zone, interphase and precipitatition in supersaturated solid solution duing aging were calculated in Al-Zn based alloys.The effect of these precipitates on alloys’ properties was discussed.Thirdly,the valence electron structures of both Al-Zn, Al-Mg, Mg-Zn segregated cells and Al-Zn-Mg segregated cell were computered. The structural models of precipitates were analyzed.Finally,the interphase energy between G.P. zone and matrix in solid solution during aging of Al-Zn based alloys was calculated.The surface charging density of the interphase was calculated too.更多还原