Conferences

Stability of the β-Mn Structure in Rapidly Quenched Fe–Mo–Cr–C Alloys at High Temperatures

  

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
http://www.materials.kiev.ua/article/1441

Abstract

High-temperature x-ray diffraction (HT-XRD) is used to study the evolution of phase states of cast and spinning 51.9Fe11.1Mo26.3Cr10.7C at.% alloys in the temperature range 293–1573 К. It is established that α- and β- Mn-like phases (χ and π, respectively) and solid solutions based on α- and γ-Fe identified by HT-XRD in the temperature range 293–978 К are metastable. A diffusion-free method of mutual transformations of the Mn-like phases in the temperature range 873–978 К is proposed. It is shown that increase in temperature in HT-XRD conditions stabilizes the metastable Mn-like phases. It is experimentally established, for the first time, that a stable β-Mn-like phase exists near the solidus in the Fe–Mo–Cr–C system. It is concluded that congruent crystallization is a way of forming the stable π-phase with Fe5MoCr2.5C composition. It is demonstrated that the stable χ-phase and equilibria with its participation, α + η + М23С6 + χ and χ + α + π + L, exist in the temperature range 1473–1523 К in the Fe–Mo–Cr–C system. It is determined that decomposition and/or mutual transformations of the metastable Mn-like phases in 51.9Fe11.1Mo26.3Cr10.7C alloys occur at Т ≈ 978 К, which is close to the temperature of the polymorphic transformation α-Mn ⇄ β-Mn in pure manganese.


FE–MO–CR–C SYSTEM, HT-XRD, RAPIDLY QUENCHED ALLOYS, RIETVELD ANALYSIS, STABLE AND METASTABLE MN-LIKE PHASES