(上海交通大學(xué) 材料科學(xué)與工程學(xué)院，上海 200240)
摘 要: 采用掃描電鏡、透射電鏡、X射線衍射等手段研究AlMg合金中常見氧化物MgO與MgAl2O4的異質(zhì)形核作用。結(jié)果表明：高溫下Al熔體與MgO、MgAl2O4發(fā)生化學(xué)反應(yīng)，在接觸界面處生成Al2O3；其中Al/MgO為多步反應(yīng)，MgAl2O4是其反應(yīng)的中間產(chǎn)物。反應(yīng)層Al2O3阻隔液態(tài)Al與MgO、MgAl2O4基底的直接接觸，在一定程度上抑制MgO和MgAl2O4對(duì)Al的形核作用。Al/MgO、Al/MgAl2O4界面反應(yīng)腐蝕原MgO與MgAl2O4的外露晶面，使新生的Al2O3晶粒呈離散化生長(zhǎng)。Al/Al2O3、Al/MgO和Al/MgAl2O4形核界面的透射分析結(jié)果表明，無論是新生相Al2O3或原MgO與MgAl2O4，均可作為異質(zhì)相基底觸發(fā)Al的異質(zhì)形核過程，但具有不同的形核潛力。
關(guān)鍵字: AlMg；氧化物；形核；界面反應(yīng)
（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
