TiAl对燃烧合成Ti_2AlC的影响

EFFECTS OF TiAl ADDITION ON COMBUSTION SYNTHESIS OF Ti_2AlC

以单质粉末Ti,Al和炭黑为原料,添加一定量燃烧合成法自制的金属间化合物TiAl,在保持总配方中Ti2AlC化学计量比不变时,研究了TiAl对燃烧合成产物的影响。结果表明:不添加或添加质量分数为20%～35%的TiAl,燃烧合成产物的主晶相均为Ti3AlC2,只含有少量Ti2AlC。产物中Ti3AlC2量随添加TiAl量增加而增加,而Ti2AlC相的含量基本不变。生成Ti2AlC和Ti3AlC2的反应是Ti-Al-C燃烧反应体系中的平行反应,实验中生成Ti3AlC2的速率大于生成Ti2AlC的速率。金属间化合物TiAl不是控制燃烧合成Ti2AlC反应速率的物质,而是控制燃烧合成Ti3AlC2反应速率的物质之一。从化学反应动力学和热力学角度探讨了TiAl对Ti-Al-C体系燃烧合成过程的影响机理。

Effects of intermetallic compound TiAl made by using combustion synthesis method on the combustion products Ti2AlC,which was prepared under stoichiometry ratio by using Ti,Al and carbon black as raw materials,were studied. The results show that the main phase of the combustion products is always Ti3AlC2 no matter with or without the addition of TiAl （20%～35%,mass fraction）,and only a small amount of Ti2AlC could be found as the second phase. The content of Ti3AlC2 increases with the increase of TiAl addition,but the content of Ti2AlC only slightly changes. The reactions to produce Ti2AlC and Ti3AlC2 are the parallel reactions of Ti-Al-C combustion reaction system. Under this test condition,the synthesis rate of Ti3AlC2 is faster than that of Ti2AlC. Even thought the intermetallic compound TiAl does not control the reaction rate of combustion synthesis of Ti2AlC,it is one of the factors to control the reaction rate of combustion synthesis of Ti3AlC2. The above experimental phenomena are discussed through the thermodynamic and kinetic point of view.