Chang H, Higginson R L, Binner J G P
Department of Materials, Loughborough University, Loughborough, LE11 3TU, U.K.
J Microsc. 2009 Jan;233(1):132-9. doi: 10.1111/j.1365-2818.2008.03103.x.
This paper considers the microstructures of an Al(Mg)-Al(2)O(3) interpenetrating composite produced by a pressureless infiltration technique. It is well known that the governing principle in pressureless infiltration in Al-Al(2)O(3) system is the wettability between the molten metal and the ceramic phase; however, the infiltration mechanism is still not well understood. The objective of this research was to observe the metal-ceramic interface to understand the infiltration mechanism better. The composite was produced using an Al-8 wt% Mg alloy and 15% dense alumina foams at 915 degrees C in a flowing N(2) atmosphere. After infiltration, the composite was characterized by a series of techniques. Thin-film samples, specifically produced across the Al(Mg)-Al(2)O(3) interface, were prepared using a dual-beam focussed ion beam and subsequently observed using transmission electron microscopy. XRD scan analysis shows that Mg(3)N(2) formed in the foam at the molten alloy-ceramic infiltration front, whereas transmission electron microscopy analysis revealed that fine AlN grains formed at the metal-ceramic interface and MgAl(2)O(4) and MgSi(2) grains formed at specific points. It is concluded that it is the reactions between Al, Mg and the N(2) atmosphere that improve the wettability between molten Al and Al(2)O(3) and induce spontaneous infiltration.
本文研究了采用无压浸渗技术制备的Al(Mg)-Al₂O₃互穿复合材料的微观结构。众所周知，Al-Al₂O₃体系无压浸渗的主导原理是熔融金属与陶瓷相之间的润湿性；然而，浸渗机制仍未得到很好的理解。本研究的目的是观察金属-陶瓷界面，以更好地理解浸渗机制。该复合材料是在915℃的流动氮气气氛中，使用Al-8 wt% Mg合金和15%的致密氧化铝泡沫制备的。浸渗后，采用一系列技术对复合材料进行了表征。使用双束聚焦离子束制备了专门穿过Al(Mg)-Al₂O₃界面的薄膜样品，并随后用透射电子显微镜进行观察。XRD扫描分析表明，在熔融合金-陶瓷浸渗前沿的泡沫中形成了Mg₃N₂，而透射电子显微镜分析显示，在金属-陶瓷界面形成了细小的AlN晶粒，在特定点形成了MgAl₂O₄和MgSi₂晶粒。得出的结论是，Al、Mg与氮气气氛之间的反应改善了熔融Al与Al₂O₃之间的润湿性，并诱导了自发浸渗。
