Fe-C-Ti-Mn合金系中TiC原位生成反应的热力学分析

根据溶液热力学理论对Fe C Ti Mn体系中TiC增强体的原位合成进行了热力学分析。计算表明,体系中TiC优先于Fe3C和Fe2Ti形成,且在热力学上比Fe3C和Fe2Ti稳定。多数情况下,TiC基体合金在液态未凝固时即可形成,而Fe3C和Fe2Ti则是在合金凝固和冷却过程中才有可能析出。随C含量增加,形成TiC和Fe3C的可能性增大;随Ti含量增加,形成Fe2Ti的可能性增大,而形成Fe3C的可能性减小;高Ti高C时,有利于形成TiC,高Ti低C时有利于形成Fe2Ti;高C低Ti时有利于形成Fe3C;添加适量的Mn既可有效抑制Fe3C的形成,又明显降低TiC的合成温度,使大多数TiC的合成反应发生在合金熔体充满铸型后的冷却、凝固过程中,可能解决TiC过早析出、熔体粘度增大、充型困难等问题。

Thermodynamic analysis on in-situ TiC synthesis in Fe-C-Ti-Mn system

A thermodynamic analysis on in-situ TiC synthesis in Fe-C-Ti-Mn system was made on the basis of solution thermodynamics theory. Calculated results show that the formation of TiC is ahead of the formation of Fe_3C and Fe_2Ti and TiC is more stable than Fe_3C and Fe_2Ti thermodynamically. Usually, TiC is formed before the solidification of matrix alloy while Fe_3C and Fe_2Ti are separated during the solidification and cooling process of the alloy. With the increase of C concentration, the possibility of TiC and Fe_3C formation are increased.Furthermore,with higher Ti concentration, the possibility of Fe_2Ti and Fe_3C formation are increased and decreased, respectively. The formation of TiC is promoted when the concentration of C and Ti are higher and that of Fe_2Ti is promoted when Ti concentration is higher and C concentration is lower.Moreover, the formation of Fe_3C is prompted when C concentration is higher and Ti concentration is lower.By addition of appropriate amount of Mn, the formation of Fe_3C is inhibited effectively and the TiC synthesis temperature reduces significantly,so that most of TiC synthesis reaction will take place in the alloy solidification and cooling process after the molten alloy fills up the cast form,thus it is possible to solve the problem of too early separation of TiC and form filling difficulty due to increase of molten alloy viscosity.