Modeling of iron-based alloy dendrite-structure formation conditions during gas atomization

High chromium cast iron alloys are widely used to produce wear resistant components. However, formation of the large carbides restricts their applied range for the components by traditional solidification techniques. The gas atomization is an effective approach to refine their structures, improve their properties and extend their application field. Based on the study of structure evolution of atomized powders of Fe-25Cr-3.9C alloy, this paper investigated the structure evolution of the atomized powders of Fe-25Cr-3.9C alloy with addition of Ni and B elements. It is found that addition of Ni and B elements make more primary lath-shaped phase be formed. As particle size decrease, width of the primary lath-shaped phase gradually decreases, and the structures are all composed of lath-shaped phase in the small powders with diameter less than 38mm. At last, a relative study between two alloys was made, and the structure formation of atomized powders was discussed.

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Iron-based MMCs by gas atomization

Metal Powder Report ◽

10.1016/s0026-0657(10)80011-6 ◽

1990 ◽

Vol 45 (1) ◽

pp. 27

Keyword(s):

Gas Atomization ◽

Iron Based

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Dicarbonyl chelates from 1-cymantrenylalkylamides with the dendrite structure: formation, photochromism, and kinetics of dark reaction with carbon monoxide

Russian Chemical Bulletin ◽

10.1007/s11172-015-1203-0 ◽

2015 ◽

Vol 64 (11) ◽

pp. 2646-2654 ◽

Cited By ~ 1

Author(s):

S. Kelbysheva ◽

L. N. Telegina ◽

O. V. Abramova ◽

T. V. Strelkova ◽

N. S. Ikonnikov ◽

...

Keyword(s):

Carbon Monoxide ◽

Structure Formation ◽

Dendrite Structure ◽

Dark Reaction ◽

Kinetics Of

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INFLUENCE OF THE TWO-STAGE SINTERING MODE ON STRUCTURE FORMATION AND PROPERTIES OF POWDERED ALL-PRESSED BIMETALLIC IRON-BASED MATERIALS

Izvestiya Vuzov Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings Powder Metallurgy аnd Functional Coatings) ◽

10.17073/1997-308x-2018-2-23-34 ◽

2018 ◽

pp. 23-34

Author(s):

B. G. Gasanov ◽

V. G. Perederiy ◽

A. D. Efimov ◽

S. S. Baev

Keyword(s):

Structure Formation ◽

Diffusion Processes ◽

Powder Materials ◽

Radial Compression ◽

High Porosity ◽

Wear Resistant ◽

Second Stage ◽

Bimetallic Materials ◽

Iron Based ◽

Resistant Layer

The paper justifies the urgency and efficiency of obtaining bimetallic iron-based materials by two-step isothermal sintering to enable forming the structure of the product bases at the first stage and activating diffusion processes in the wear-resistant layer only at the second stage to eliminate any high-porosity areas and brittle inclusions at interlayer boundaries typical for powder materials doped with carbides, nitrides and borides. The analysis of equation solutions for diffusion in two-component heterogeneous powder systems made it possible to propose an option for determining the time and temperature of homogenizing sintering of bimetallic materials taking into account grain-size distribution of powders, concentration and partial diffusion coefficients of components, charge bulk density, initial and final porosity of the products. Experiments proved that bimetallic materials containing 15– 20 wt.% of chromium carbide, 20–25 wt.% of ferrochromium and iron as the rest component in the wear-resistant layer charge have the best combination of hardness, wear resistance and radial compression strength after sintering in a chamber furnace in protective medium at 1150–1180 °C with a holding time of 1,5–2,0 hours at the first stage, and in an induction furnace at 1350– 1370 °C for 25–35 s with a heating rate of 450–470 °C/s at the second stage. Structure formation peculiarities of the interlayer boundaries and wear-resistant layer during two-step sintering of all-pressed bimetallic materials are shown. It is found that for high-temperature sintering by high-frequency (8 or 16 kHz) heating at the second stage, the depth of chromium diffusion from the wear-resistant layer to the matrix is 120–130 μm, and Cr concentration in various points of interlayer and interparticle boundaries varies between 1 and 30 wt.% thus allowing formation of a transition layer with a structure consisting of a ferritic-austenitic matrix with martensitic colonies and dispersed particles of (Cr,Fe)23C6, (Cr,Fe)7C3 and (Cr,Fe)3C2 ferrochromium carbides uniformly distributed over the volume.

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The Influence of Structure Formation Conditions of the Composite on the Mass Transfer Processes

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/753/4/042047 ◽

2020 ◽

Vol 753 ◽

pp. 042047

Author(s):

S V Fedosov ◽

V Eu Roumyantseva ◽

V S Konovalova ◽

I N Goglev

Keyword(s):

Mass Transfer ◽

Structure Formation ◽

Transfer Processes ◽

Mass Transfer Processes ◽

Formation Conditions

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A TEM study of the effect of oxygen on nanocavity formation and precipitation in rapid - solidified Fe-16Ni-9Cr stainless steels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171237 ◽

1994 ◽

Vol 52 ◽

pp. 700-701

Author(s):

S. Wisutmethangoon ◽

T. F. Kelly ◽

J.E. Flinn

Keyword(s):

Stainless Steels ◽

High Mobility ◽

Hot Extrusion ◽

Extrusion Ratio ◽

Gas Atomization ◽

Cavity Formation ◽

Nucleation Sites ◽

Heat Treated ◽

Different Types ◽

Effect Of Oxygen

Vacancies are introduced into the crystal phase during quenching of rapid solidified materials. Cavity formation occurs because of the coalescence of the vacancies into a cluster. However, because of the high mobility of vacancies at high temperature, most of them will diffuse back into the liquid phase, and some will be lost to defects such as dislocations. Oxygen is known to stabilize cavities by decreasing the surface energy through a chemisorption process. These stabilized cavities, furthermore, act as effective nucleation sites for precipitates to form during aging. Four different types of powders with different oxygen contents were prepared by gas atomization processing. The atomized powders were then consolidated by hot extrusion at 900 °C with an extrusion ratio 10,5:1. After consolidation, specimens were heat treated at 1000 °C for 1 hr followed by water quenching. Finally, the specimens were aged at 600 °C for about 800 hrs. TEM samples were prepared from the gripends of tensile specimens of both unaged and aged alloys.

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