铁粉部分预合金化过程中间隙元素的定向迁移

采用与水雾化铁粉纯度相同的致密铁铸锭作试样 ,通过在其表面涂覆合金元素粉末层进行部分预合金化扩散处理 ,以研究部分预合金化铁粉的压缩性改善的机理 .研究发现 ,在铁粉扩散处理过程中 ,由于部分合金化铁粉中的合金化区域产生了铁晶格畸变 ,导致该区域的体系能量升高 ,将未合金化区域中的间隙原子如C ,N ,O等吸引到合金化区域 ,产生未合金化区域中的间隙原子向合金化区域的定向迁移 ,未合金化区域产生“自纯化”效应 .实验结果表明 ,随着扩散处理温度的提高和处理时间的延长 ,未合金化区域中间隙元素的含量降低程度也增大 ;间隙原子自未合金化区域向合金化区域的迁移过程符合扩散动力学规律

Directional mobility of interstitial atoms from unalloyed zone to alloyed zone during partial alloying of iron powder particles

Iron ingot with the same chemical compositions as water atomized iron powder was utilized for specimens coated with alloying element powder layer to investigate the plasticity improving mechanism of partially alloyed iron powders. It was found that, self purification of the unalloyed zone in the partially alloyed iron powder particle occurs from mobility of the interstitial atoms such as C, N, O from the unalloyed zone to the alloyed zone. The driving force for the interstitial atom directional mobility is the increase in systematic energy caused by iron lattice distortion after alloying elements such as nickel and copper dissolved in iron lattice. Also, the content of the interstitial atoms in the unalloyed zone of iron reduces with increasing diffusion temperature and prolonging holding time. In general, the directional mobility of the interstitials meets well with the diffusion dynamic law.