Projection of the Solidus Surface of the Fе–Mo–C System at 0−40 at.% Carbon


I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2011, #07/08


The solidus projection of the Fe–Mo–C system in the composition range 0−40 at.% C is constructed for the first time using EDX, SEM, HT-DTA, HT-XRD, Pirani–Alterthum method, Vickers microhardness measurement, and CALHPAD modeling technique. It is established that there are three-phase equilibria М6C + (Мо2С) + (Мо), М6С + (Мо) + σ, М6С + σ + R, М6С + R + (α-Fe), М6С + (α-Fe) + (γ-Fe), М6С + (γ-Fe) + (Мо2С) and (γ-Fe) + (Мо2С) + Fe2MoC on the solidus surface, whose temperatures are decreasing from 1484 to 1100 ºС. It is shown that М6С-carbon intermetallide is a linear phase in terms of carbon on the solidus surface with the homogeneity range Fe38,2–45,3Mo47,5–40,4C14,3 for metal components, within which the lattice parameters change from 1.1152(3) to 1.1072(8) nm. CALPHAD modeling shows that there are three-phase equilibria with participation of orthorhombic stabilized (Fe3C)-cementite and monoclinic molybdenum Fe2MoC-cementite: (γ-Fe) + (Fe3C) + С, (γ-Fe) + (Fe3C) + Fe2MoC, (Fe3C) + Fe2MoC + С, Fe2MoC + (Mo2C) + C on the solidus besides the above-mentioned equilibria.