搅拌摩擦加工制备石墨烯/Al复合材料的界面微观结构

Interface microstructure of graphene/Al composites prepared by friction stir processing

以纯净石墨烯为原料,采用搅拌摩擦加工法制备石墨烯/Al复合材料,主要通过透射电镜等手段观察分析复合材料石墨烯?Al的两种界面,即石墨烯平面?Al、石墨烯边缘?Al的界面微观结构,并对界面形成机制进行了分析。结果表明:石墨烯平面?Al界面清晰,是典型的机械结合界面;而石墨烯边缘?Al界面存在过渡,且在其附近偶尔还发现Al4C3的分布,此区域主要以扩散结合并可能具有部分反应(扩散+部分反应)的界面形式存在。复合材料的界面形成机制与石墨烯不同位置的C原子活性有关,平面内C原子的大π共轭结构使其高度惰性,形成机械结合界面;而搅拌摩擦加工过程对石墨烯的破坏主要发生在边缘,由于C—C键合被破坏,石墨烯边缘活泼的C原子与Al基通过C—Al原子的相互作用而形成扩散+部分反应的过渡界面。

The graphene/Al composites were prepared by friction stir processing used pristine graphene as the raw materials.The interface between graphene and the matrix could be divided into two types,namely graphene plane-Al and graphene edges-Al,graphene materials exhibit a unique two-dimension structure.Two types of interface microstructure were mainly observed by TEM and the interface formation mechanisms were analyzed.The results show that it is clean and well bonded in the graphene plane-Al,illustrating a mechanical bonding.Nevertheless,a transition zone,Al4C3 occasionally detects near the zone,which is found in the graphene edge-Al,this zone is estimated to exist as an interface combined with diffusion and partial reaction bonding.The interface formation mechanisms are related to the activity of C atoms in different graphene locations.The C atoms in the graphene plane are highly inert for the large conjugatedπbond structure,and therefore,the mechanical bonding interface forms here.However,the C atoms at the graphene edge are active owing to C—C bonds dissociation in friction stir processing,and diffusion and partial reaction bonding with interface transition forms as the result of atomic-scale interaction between C and Al.