不同工艺条件下燃烧合成Fe3Al合金的显微结构特征

利用铁粉铝粉间的放热化学反应合成了Ｆｅ３Ａｌ合金，分析比较了热爆、热爆加压和自蔓延三种工艺条件下产物形成过程及组织结构特点，研究表明：合成开始时首先分别在粗大铁粉和细小铁粉处形成含铝富铁。相和ｎ（Ｆｅ３Ａｌ５）型化合物两种过渡相，热爆合成温度较高，两种过渡相间可充分反应生成成份均匀的ａ相，并经较快冷却后亚稳定存在于室温；热爆加压合成时，加压系统的吸热不仅使合成反应移到温度较低的Ｂ２相区中进行，而且冷却加快使反应后的扩散过程无法充分进行，产物由成份不均匀的Ｂ２相和反应后残留的ａ相组成。

EFFECTS OF COMBUSTION CONDITION ON MICROSTRUCTURE OF Fe3Al ALLOY PREPARED BY SHS

Th Fe3Al alloy was prepared by combustion synthesis(SHS)starting from compacts ofmixed Fe and Al powders, and three kinds of combustion conditions(thermal explosion,combined thermal explosion with hotpressing and combined self-propagating withquenching)were chosen to study the structure of products and their evolution during synthesis,ResuIts of the quenched sample showed that :lots of granular Al-riched n(Fe2Al5)phas-es and a-Fe solid solution were formed at the very beginning of synthesis,then thesp twophases gradually transformed into one homogeneous phase through diffusion beowcen pnas-es.For the sample of thermal explosion mode,one homogeneous a-phase was obtained dueto its high synthesis temperature,and it did not reach stable state-DO3 phase because thecooling rate was not low enough to ensure the transformation into stable state to be carriedout.However,the sample of combined synthesis with hot-pressing for densification showedsubstantial incompleteness of reaction,the structure of alloy consisted of the B2 phase andinhomogeneous aphase,the reason for it was probably the Iower synthesis temperature andmore rapid cooling rate than the exthermal explosion due to endothermic effect of pressurizing system.