电场诱导Fe-Ti-C体系低温燃烧合成显微组织演变

Microstructure Evolution of of Fe-Ti-C System Synthesized by Low Temperature Combustion Induced in Electric Field

采用Gleeble-1500D热模拟机,通过对质量分数55%(Ti+C)-45%Fe粉末压坯分别升温至250～800℃的解析实验,研究Fe-Ti-C体系在电场诱导下低温燃烧合成的显微组织演变。结果表明:在电场和大热流密度的共同作用下,体系的点火温度可大幅降低。当加热温度在250～350℃之间,体系虽未发生化学反应,但显微结构在一定程度随温度而发生变化;当加热温度在350～470℃范围内,体系被点燃发生“热爆”现象,而在燃烧合成反应前期,合成TiC的反应优先发生;当加热温度提高到470～670℃,合成TiC反应发生的同时还伴随有合成Fe2Ti的反应;然而随加热温度进一步提高到670～800℃,Fe2Ti会发生部分分解,进而使得合成TiC的反应继续进行。当温度达到800℃左右,该合成反应全部完成,产物由Fe、TiC和少量Fe2Ti组成。此外,通过合成反应所得呈圆球状、细小的TiC颗粒均匀地分布在Fe基体中,且随加热温度的提高而有所长大。

The microstructure evolution of Fe-Ti-C system synthesized by low temperature combustion in electric field was studied using the mixture powders compacts of 55wt%（Ti＋C）-45wt%Fe heated to 250-800 ℃ by an analytical experiment of Gleeble-1500D thermal simulation equipment. The results show that the ignition temperature of Fe-Ti-C system can be greatly decreased under the action of electric field and high thermal density. Firstly, the microstructure changes with the heating temperature from 250 ℃ to 350℃ although no reaction occurred in the system. The system can be ignited so that the phenomenon of“thermal explosion” occurred from 350℃ to 470℃, with a prior TiC synthesis reaction. As the temperature increased continuously from 470℃ to 670℃, the TiC synthesis reaction followed by another Fe2Ti synthesis reaction. But a part of Fe2Ti can be decompounded when heated to 670-800℃, so that the TiC synthesis reaction went on and finished completely at 800℃. As a result, the synthesized products consisted of Fe, TiC and a little of Fe2Ti. In addition, the microstructure showed that fine TiC spherical particles were uniformly distributed in the Fe matrix.