Transformation of Fe–C system to high pressured hexagonal structures by mechanical alloying of elemental powders

The structure changes of the iron–carbon system from Fe75C25 to Fe50C50 and Ni75C25 by mechanical alloying of elemental powders were studied using X-ray diffraction and 57Fe Mössbauer spectroscopy. Super-saturated hexagonal solid solutions were formed as bcc→orthorhombic structure (cementite)→hcp in the Fe–C system and fcc→hcp in Ni75C25. It is considered that the locally high compression is generated by the forced solid dissolving of large amount of carbon atoms into the interstitially octahedral sites.