On the Solidification of Pure C-Cr-Fe Alloys

Chicco, Bruno; Thorpe, W.R.

doi:10.1080/09534962.1992.11819114

Cited by 4 publications

(3 citation statements)

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“…Later work by Chicco and Thorpe 21) has confirmed the positions of U 1 and U 2 and has restated the equilibrium reactions as:…”

Section: Microstructure and Solidification Sequences In 30 % Cr Ironmentioning

confidence: 97%

“…Much of the discussion and uncertainty in the literature 17,18,21,22) regarding the equilibrium positions and nature of the peritectic reactions at U 1 and U 2 has centred on the effects of cooling rate. As in simple binary systems, a peritectic reaction can be suppressed by fast cooling which limits the time for diffusion through the barrier product phase.…”

Section: Microstructure and Solidification Sequences In 30 % Cr Ironmentioning

confidence: 99%

“…10(c)). During their phase equilibria studies, 18,21) Thorpe and Chicco noted that, for an alloy containing 29 wt% Cr and 1.7 wt% C, the LϩdFe → ← gFe reaction appeared to go almost to completion and they showed microstructural evidence of this reaction. However, similar microstruatural features were not seen in the austenite dendritic microstructures of alloy A or B.…”

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An Unusual Structure of an As-cast 30 % Cr Alloy White Iron

2005

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An unusual microstructure of an as-cast 30 wt% Cr and 2.26 wt% C iron has been examined by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the microstructure varied with positions in the cast bar. In the upper part of the cast bar where the cooling rate was faster, the matrix was essentially austenite with some patches of ferrite-plus-precipitated carbides as dendritic regions. Whereas, the central and the lower parts of the cast bar where cooling rates were slower, there was less austenite with greater amount of ferritic zones. The microstructure of core regions at the centre of the dendritic ferrite-plus-precipitated carbides zones contained interconnected carbides that are believed to be the product of a peritectic reaction. TEM examination confirmed that these peritectic carbides were M 7 C 3 type. Bainite and martensite were also observed in the transition zones close to the ferrite-plus-precipitated carbides zones. These were believed to result from solid-state decomposition of the dendritic austenite in the later stage of cooling.KEY WORDS: high chromium cast iron; microstructure; electron microscopy; peritectic reaction.was sectioned transversely to give specimens with an approximate thickness of 15 mm. Sample Preparation for Microstructural Investi-gation Metallographic specimens for optical microscopy (OM) and scanning electron microscopy (SEM) were mounted in resin, ground on silicon carbide papers to 1 200 grit and then polished to 1 mm diamond finish. The etchants used were (1) 50 mL of HCl and 10 g of Na 2 S 2 O 5 in 100 mL distilled water, to reveal the ferritic and austenitic microstructure, and (2) 10 % HCl in methanol for 6 h for deep etching to examine the morphology of carbides. The microstructures were observed using a JEOL JSM-5410LV scanning electron microscope. Chemical microanalysis was performed using an Oxford Instruments ATW2 X-ray Spectrometer. The SEM was operated at 20 kV using a working distance of 17 mm from the objective lens.Thin foils for transmission electron microscopy (TEM) were prepared by sectioning specimens, perpendicular to the axis of the as-cast cylindrical rod, with a cubic boron nitride saw to obtain slices with a thickness of about 200 mm. These were then ground manually on silicon carbide papers (down to 1 200 grit) to reduce their thickness to about 80 mm. Discs, 3 mm in diameter, were then punched out and thinned with a Struers, Tenupol-3 twin-jet electropolisher operated at 15 V and approximately 20 mA, using a solution containing 10% perchloric acid and 30% of 2-butoxyethanol in absolute ethanol maintained at Ϫ15°C. The thin samples were argon-ion-beam-thinned using a Gatan model 600 DIF Duo Mill ion beam thinner for final stage thinning. They were then examined using a JEOL JEM-2010 scanning-transmission electron microscope, operated at 200 kV. Hardness MeasurementThe specimens prepared for SEM were also used for hardness determination. A Galileo microhardness tester was used to measur...

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“…Later work by Chicco and Thorpe 21) has confirmed the positions of U 1 and U 2 and has restated the equilibrium reactions as:…”

Section: Microstructure and Solidification Sequences In 30 % Cr Ironmentioning

confidence: 97%

Section: Microstructure and Solidification Sequences In 30 % Cr Ironmentioning

confidence: 99%

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confidence: 99%

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