Stable High-Temperature π-Phase in the Fe–Mo–Cr–C System: Crystalline Structure and Properties

Abstract

A bulk sample of composition 51.9Fe11.1Mo26.3Cr10.7C at.% with β-Mn structure is prepared and examined by X-ray diffraction, high-temperature differential thermal analysis, and light microcopy. The stable high-temperature π phase of β-Mn type crystallizes congruently from the liquid phase in the Fe–Mo–Cr–C system, the singular point being found at about 51.9Fe11.1Mo26.3Cr10.7C at.% and 1520 ± 25 K. The structural characteristics of the π phase are presented. Its thermal expansion coefficient is 14.32 ∙ 10^–6 K^–1 and microhardness 15.9 GPa. The π phase is characterized by high chemical resistance to inorganic acids and their mixtures from room temperature up to the boiling point.