【作者】 李云雯；

【导师】 高英俊；

【作者基本信息】 广西大学 ， 理论物理， 2004， 硕士

【摘要】 本文分析了Al-Mg-Si合金中的相空间和相界面的价电子结构，研究了其对合金性能的影响。主要内容为： 1．在Al-Mg-Si合金固溶体中主要存在着三类晶胞：α-Al晶胞，Mg₂Si晶胞和Si晶胞，运用固体与分子经验电子理论（简称EET理论），对各相的价电子结构、相界面如α-Al／Mg₂Si（β）界面、α-Al／β-Si界面的面电荷密度以及β-Si和Mg₂Si（β）的键密度进行了计算。 2．对影响合金性能的结构因子F、相结构形成因子S等进行了计算。 3．对计算结果进行了分析。 在Al-Mg-Si系合金的固溶体中，Mg原子和Si原子之间存在强烈的相互作用，容易形成Mg₂Si（β相）偏聚区。同时，加入过量的硅，可以更好地、更多地生成Mg₂Si，这些细小偏聚区分散在固溶体中有效地抑制着基体Al晶粒的长大，起到了弥散强化的作用；由于硅的最短键的键密度比Mg₂Si最短键的键密度要大，又抑制了Mg₂Si晶粒的生长，使晶粒得到细化。 Al-Mg-Si系合金在时效过程中的二元析出相Mg₂Si的（001）界面与基体Al（001）界面电子密度不连续，且相差很大；此外，β-Si的（100）界面与基体α-Al（110）界面电子密度也不连续，并且相差也很大，二广西大学硕士学位论文者共同导致合金的性能下降。同时相结构因子也决定了合金性能的下降。更多还原

【Abstract】 The valence electron structures of maid phases, phase, interphase boundaries and its effects on the properties of Al-Mg-Si based alloy were analyzed. It is listed as follows:1.The solid solution of Al-Mg-Si based alloy was contained three main cells:a-Al cell, Si cell and Mg2Si cell. According to the Empirical Electronic Theory in solid and molecules (EET), the valence electronic structures of these cell, the valence electron structures of phase and interphase boundaries between the matrix and the cells above, the bonding density lie in strongest bonding of β-Si and Mg2Si (β) and the precipitations were calculated.2. The phase configurations, F and S were calculated which also affect the properties of the alloy.3. Through above analysis, the results show that:The strong interaction of Mg and Si in solid solution of Al-Mg-Si based alloy, which lead to the behavior of Mg2Si segregation. The excess Si contentcan lead to grow more Mg2Si. The electon density lie in strongest bonding of Si is larger than that of Mg2Si. The strong segregations are restrained the growth of the matrix and make the grain fined.On the interphase boundaries between the matrix and the precipitates, such as (001)Mg2Si//(001)Al,(100)Si//(110)Al. The electronic density are notcontinued in Al-Mg-Si based alloy, which lead to reduce of the properties of the alloy. Furthermore, the phase configurations also lead to reduce the properties of alloy.更多还原