(上海交通大学 材料科学与工程学院，上海 200240)
摘 要: 采用扫描电镜、透射电镜、X射线衍射等手段研究AlMg合金中常见氧化物MgO与MgAl2O4的异质形核作用。结果表明：高温下Al熔体与MgO、MgAl2O4发生化学反应，在接触界面处生成Al2O3；其中Al/MgO为多步反应，MgAl2O4是其反应的中间产物。反应层Al2O3阻隔液态Al与MgO、MgAl2O4基底的直接接触，在一定程度上抑制MgO和MgAl2O4对Al的形核作用。Al/MgO、Al/MgAl2O4界面反应腐蚀原MgO与MgAl2O4的外露晶面，使新生的Al2O3晶粒呈离散化生长。Al/Al2O3、Al/MgO和Al/MgAl2O4形核界面的透射分析结果表明，无论是新生相Al2O3或原MgO与MgAl2O4，均可作为异质相基底触发Al的异质形核过程，但具有不同的形核潜力。
关键字: AlMg；氧化物；形核；界面反应
（School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China）
Abstract:The nucleation behavior of common oxides MgO and MgAl2O4 in AlMg alloys were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results show that, at high temperatures, Al melt would react with MgO and MgAl2O4 substrates to formed Al2O3 at contacting interface. Among them, the reaction of Al/MgO is a multi-step reaction and MgAl2O4 is an intermediate reaction product. The interfacial reaction layer Al2O3 hinders liquid Al from contacting MgO or MgAl2O4 substrates, inhibiting their interfacial reaction to some extent. The interfacial reaction corrodes the exposed planes of original substrates, leading to scattered growth orientations of the new grains. TEM results of three detected nucleation interfaces Al/Al2O3, Al/MgO and Al/MgAl2O4 indicate that either new formed Al2O3 or original MgO and MgAl2O4 could all act as effective heterogeneous substrates to trigger nucleation process of Al, but with different nucleation potencies.
Key words: AlMg; oxide; nucleation; interfacial reaction
