Al-Mg合金直接氧化Al2O3形成模型

根据对Al-Mg合金直接氧化合成Al/ Al2O3存在Mg的挥发及线性生长动力学特点的分析,在把表面MgO形成过程看成是Al2O3向MgO中的溶解过程并认为MgO部分为n型氧化物时,氧化过程有利于Al2O3的形成:Al-Mg合金直接氧化过程中,Mg的挥发满足Al2O3形成的两个条件,Mg挥发促进表层P型MgO的生长和内层n型MgO中Al2O3的形成,促进MgO向MgAl2O4的转变过程;MgAl2O4在Al2O3的形成中起重要作用,MgO向MgAl2O4转变过程中,生长应力导致MgAl2O4中形成间隙,Al熔体通过此间隙向氧化前沿进行渗流输运;Al2O3的生长动力学取决于MgO向MgAl2O4转变的速度,MgO向MgAl2O4转变速度加快是Al/Al2O3生长动力学呈线性关系的根本原因.

Formation Model of Alumina in the Course of Directed Oxidation of Aluminum Magnesium Alloy

By analyzing the characteristics of magnesium volatilization and linear growth kinetic of Al/ Al_2O_(3 )in directed oxidation of Al-Mg alloy, as the formation process of MgO is considered to be the process of which Al_2O_(3)dissolved in the scale MgO and MgO is partially n-type oxide, formation condition of Al_2O_(3)is established easily in the coure of oxidation. Volatilization of magnesium is to promote the growth of p-type MgO in the surface layer and the formation of Al_2O_(3 )in the inner layer of n-type MgO, and to promote the transformation of MgO toMgAl_2O_(4).MgAl_2O_(4)plays an important role in the formation process of Al_2O_(3), growth stress between MgO and MgAl_2O_(4)cause the formation of cavity in the MgAl_2O_(4 )and aluminum alloy melts is easier to transfer to oxidation front by means of this cavity. The transformation velocity ofMgO to MgAl_2O_(4 )depends on growth kinetic of Al_2O_(3),the faster transformation velocity of MgO to MgAl_2O_(4)is main reason that growth kinetic of Al/Al_2O_(3)transformation exhibits linear relationship.