电场对燃烧合成TiC-Al_2O_3-Al复合材料显微组织的影响

Microstructure Formation Mechanism of the Combustion Synthesis of TiC-Al_2O_3-Al Composites under Electric Field

以3TiO2+3C+(4+x)Al反应体系为对象,利用电场的诱发作用和燃烧合成过程中形成的液态Al对合成产物的渗透作用,旨在直接燃烧合成致密的TiC-Al2O3-Al复合材料,着重研究了电场对合成材料显微组织的影响。结果表明,不同电场作用方式直接影响合成材料的组织结构;随着电场强度增加,Al2O3和TiC晶粒尺寸逐渐减小,致密性提高;在过余Al量x=14mol、外加电场E=25V/cm一直作用至SHS反应完毕条件下,合成复合材料组织中Al2O3和TiC晶粒细小,TiC呈近球状,并均匀分布于金属Al中;合成材料具有明显的韧性断裂特征。

By taking 3TiO2 + 3C + (4+x)Al as a reaction system,a dense TiC-Al2O3-Al composite was directly fabricated by an electric field inducing combustion synthesis process and the molten Al formed during the process penetrating into the synthesized products.Effect of different electric field application methods and field strength on microstructures of the combustion synthesized composite was investigated.The results show that the imposition an external electric field application method plays a significant role in influencing microstructures of the products.In addition,with increasing of field strength the grain size of Al2O3 and TiC particles decrease gradually and the density of the composites are improved.In case of x=14 mol,with E=25 V/cm applied at the start of the reaction and stopped at the finish of the combustion reaction,a dense TiC-Al2O3-Al composite has been successfully fabricated,in which TiC and Al2O3 particles are fine and uniformly distribute in metal Al.As a result,the composites have obvious features of tough fracture.