Stability of the α-Mn structure in rapidly solidified Fe–Mo–Cr–C alloys at high temperatures

High-temperature X-ray diffraction is used to study the evolution of phase states of rapidly solidified $ Fe_{64.9} %$ Mo_{19.6} %$ Cr_{14.5} $C (at.%) alloy during heating from room to solidus temperatures. The α- and β-Mn-like phases (χ and π, respectively), as well as bcc phases of various compos...
Ausführliche Beschreibung

High-temperature X-ray diffraction is used to study the evolution of phase states of rapidly solidified $ Fe_{64.9} %$ Mo_{19.6} %$ Cr_{14.5} $C (at.%) alloy during heating from room to solidus temperatures. The α- and β-Mn-like phases (χ and π, respectively), as well as bcc phases of various composition ($ α_{1} $, $ α_{2} $, α), η-carbon intermetallic ($ M_{6} $C), and R- and fcc phases are identified in the alloy. It is established that the χ-phase is stable in this alloy at high temperatures: it forms during heating in the range 973–1073 K, changes its chemical composition in the range 1073–1273 K, which remains unchanged at 1073–1473 K, and decomposes in the range 1473–1523 K; when it is heated, its relative amount and lattice parameter symbatically change from 20 to 55 wt.% and from 0.9061 to 0.9170 nm, the coefficient of thermal expansion being 16.65∙$ 10^{–6} $ $ K^{–1} $. The existence of equilibrium regions with participation of the stable χ-phase, γ + α + χ + R, χ + γ + η + α, χ + η + γ + α, and χ + α + η + R, has been established in the Fe–Mo–Cr–C phase diagram for the first time. It is shown that the π-phase, found in the initial spinning alloy, is metastable. This phase abruptly changes its composition near 842 K and completely decomposes in the range 923–1073 K. When heated in the range 293–923 K, its relative amount and lattice parameter vary from 50 to 8 wt.% and from 0.6346 to 0.6401 nm, respectively, the coefficient of thermal expansion being 2.083∙$ 10^{–6} $ $ K^{–1} $. The coefficients of thermal expansion of the η- and α-phases are 15.257∙$ 10^{–6} $ and 7.117∙$ 10^{–6} $ $ K^{–1} $. It is revealed that the temperature of full decomposition of the metastable β-Mn-like phase and appearance of the stable α-Mn-like phase in conditions of high-temperature X-ray diffraction is close to 978 K of α-Mn→ β-Mn polymorphic transformation in pure manganese. The high-temperature X-ray diffraction experiment indicates that π→α transformations of metastable phases and γ→α transformations of stable phases are diffusionless in this alloy. Ausführliche Beschreibung

Autor*in:	Velikanova, T. A. [verfasserIn] Karpets, M. V. [verfasserIn] Kuprin, V. V. [verfasserIn]

Format:	E-Artikel
Sprache:	Englisch

Erschienen:	2013

Schlagwörter:	Mn-like phases spinning method high-temperature X-ray diffraction diffusionless transformations coefficient of thermal expansion Fe–Mo–Cr–C phase diagram

Übergeordnetes Werk:	Enthalten in: Powder metallurgy and metal ceramics - Dordrecht [u.a.] : Springer Science + Business Media B.V, 1962, 52(2013), 3-4 vom: Juli, Seite 212-222
Übergeordnetes Werk:	volume:52 ; year:2013 ; number:3-4 ; month:07 ; pages:212-222

Links:	Volltext

DOI / URN:	10.1007/s11106-013-9515-9

Katalog-ID:	SPR016788869