Precipitation Behavior of Fe-Al-O Inclusions under Unidirectional Solidification of Fe-30mass%Ni Alloys Saturated with CaO-Al2O3 Slags.

Medium Manganese Transformation Induced Plastic (Mn-TRIP) steels are expected to be a new generation of advanced high strength sheet steels due to their excellent balance between material cost and mechanical properties. During the solidification process, AlN precipitates at the grain boundary, which leads to the serious deterioration of hot ductility. However, the precipitation of AlN in Mn-TRIP steel has not been clear. In this study, the chemical compositions, morphology, size distribution, and the precipitation behavior of AlN inclusion in an Fe-0.5Al-2.0Mn alloy were studied under the continuous unidirectional solidification process. The results show that there are two types of nitride inclusions in the Fe-0.5Al-2.0Mn alloy: AlN inclusion and complex inclusion of Al2O3-AlN. The planar sections of most AlN particles are hexagonal. Based on the thermodynamic calculation, it was found that the content of Al has a large effect on the stability of Al2O3 and AlN. When the content of Al increases, the molten iron can be changed from saturated by Al2O3 to saturated by AlN. During the solidification process, the precipitation of Al2O3 inclusions occurred at the beginning of the solidification process. The precipitation of AlN inclusions occurred when the contents of Al and N exceeded the equilibrium value and grew until the end of the solidification. The precipitation conditions of AlN inclusion in the Fe-0.5Al-2.0Mn alloy during the solidification process were discussed. The precipitation and the amount of precipitate of AlN inclusions depend on the initial contents of Al, N, and O. It was found that the precipitation of AlN inclusions can be controlled by reducing the initial content of N to less than 0.0072 mass%.

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Transient Unidirectional Solidification, Microstructure and Intermetallics in Sn-Ni Alloys

Materials Research ◽

10.1590/1980-5373-mr-2017-1099 ◽

2018 ◽

Vol 21 (suppl 1) ◽

Cited By ~ 4

Author(s):

Clarissa Barros da Cruz ◽

Rafael Kakitani ◽

Marcella Gautê Cavalcante Xavierb ◽

Bismarck Luiz Silva ◽

Amauri Garcia ◽

...

Keyword(s):

Unidirectional Solidification ◽

Solidification Microstructure ◽

Ni Alloys

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Unidirectional solidification of monovariant eutectic Cu-Mg-Ni alloys

Journal of Crystal Growth ◽

10.1016/0022-0248(72)90203-5 ◽

1972 ◽

Vol 16 (3) ◽

pp. 209-214 ◽

Cited By ~ 10

Author(s):

P.J. Fehrenbach ◽

H.W. Kerr ◽

P. Niessen

Keyword(s):

Unidirectional Solidification ◽

Ni Alloys

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Precipitation Behavior of Nitride Inclusions in K418 Alloy under the Continuous Unidirectional Solidification Process

ISIJ International ◽

10.2355/isijinternational.isijint-2020-345 ◽

2020 ◽

Author(s):

Fan Yang ◽

Wencheng Zhao ◽

Yuan Hou ◽

Xiliang Guo ◽

Qiang Li ◽

...

Keyword(s):

Solidification Process ◽

Unidirectional Solidification ◽

Precipitation Behavior

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Precipitation in Al-Li-Cu Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096941 ◽

1981 ◽

Vol 39 ◽

pp. 44-45

Author(s):

J. E. O'Neal ◽

K. K. Sankaran

Keyword(s):

Electron Microscopy ◽

Age Hardening ◽

Precipitation Behavior ◽

Zone Formation ◽

Specific Strength ◽

Hardening Behavior ◽

Cu Alloys ◽

High Specific Strength ◽

Transmission Electron ◽

Structural Applications

Al-Li-Cu alloys combine high specific strength and high specific modulus and are potential candidates for aircraft structural applications. As part of an effort to optimize Al-Li-Cu alloys for specific applications, precipitation in these alloys was studied for a range of compositions, and the mechanical behavior was correlated with the microstructures.Alloys with nominal compositions of Al-4Cu-2Li-0.2Zr, Al-2.5Cu-2.5Li-0.2Zr, and Al-l.5Cu-2.5Li-0.5Mn were argon-atomized into powder at solidification rates ≈ 103°C/s. Powders were consolidated into bar stock by vacuum pressing and extruding at 400°C. Alloy specimens were solution annealed at 530°C and aged at temperatures up to 250°C, and the resultant precipitation was studied by transmission electron microscopy (TEM).The low-temperature (≲100°C) precipitation behavior of the Al-4Cu-2Li-0.2Zr alloy is a combination of the separate precipitation behaviors of Al-Cu and Al-Li alloys. The age-hardening behavior at these temperatures is characteristic of Guinier-Preston (GP) zone formation, with additional strengthening resulting from the coherent precipitation of δ’ (Al3Li, Ll2 structure), the presence of which is revealed by the selected-area diffraction pattern (SADP) shown in Figure la.

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The coprecipitation of Cr3P and Cr in Cu

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105886 ◽

1988 ◽

Vol 46 ◽

pp. 764-765

Author(s):

M.J. Witcomb ◽

U. Dahmen ◽

K.H. Westmacott

Keyword(s):

Orientation Relationship ◽

Interface Structure ◽

Model System ◽

Relative Orientation ◽

Age Hardening ◽

Precipitation Behavior ◽

Solution Treated ◽

Small Needle ◽

Diffraction Patterns ◽

Interface Structures

Cu-Cr age-hardening alloys are of interest as a model system for the investigation of fcc/bcc interface structures. Several past studies have investigated the morphology and interface structure of Cr precipitates in a Cu matrix (1-3) and good success has been achieved in understanding the crystallography and strain contrast of small needle-shaped precipitates. The present study investigates the effect of small amounts of phosphorous on the precipitation behavior of Cu-Cr alloys.The same Cu-0.3% Cr alloy as was used in earlier work was rolled to a thickness of 150 μm, solution treated in vacuum at 1050°C for 1h followed by quenching and annealing for various times at 820 and 863°C.Two laths and their corresponding diffraction patterns in an alloy aged 2h at 820°C are shown in correct relative orientation in Fig. 1. To within the limit of accuracy of the diffraction patterns the orientation relationship was that of Kurdjumov-Sachs (KS), i.e. parallel close-packed planes and directions.

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Microstructures of Ti-1.5 w/o Ni Alloys with Mo and A1 Additions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113895 ◽

1975 ◽

Vol 33 ◽

pp. 54-55

Author(s):

Anna C. Fraker

Keyword(s):

Corrosion Resistance ◽

Beneficial Effect ◽

Crevice Corrosion ◽

Local Corrosion ◽

Precipitate Size ◽

Ni Alloys

Small amounts of nickel are added to titanium to improve the crevice corrosion resistance but this results in an alloy which has sheet fabrication difficulties and is subject to the formation of large Ti2Ni precipitates. These large precipitates can serve as local corrosion sites; but in a smaller more widely dispersed form, they can have a beneficial effect on crevice corrosion resistance. The purpose of the present work is to show that the addition of a small amount of Mo to the Ti-1.5Ni alloy reduces the Ti2Ni precipitate size and produces a more elongated grained microstructure. It has recently been reported that small additions of Mo to Ti-0.8 to lw/o Ni alloys produce good crevice corrosion resistance and improved fabrication properties.

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Spherulite Structures in a Melt Spun Fe-Ni Austenitic Steel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117339 ◽

1985 ◽

Vol 43 ◽

pp. 52-53

Author(s):

G. M. Michal ◽

T. K. Glasgow ◽

T. J. Moore

Keyword(s):

Austenitic Steel ◽

Room Temperature ◽

Elevated Temperatures ◽

Large Range ◽

Amorphous Structure ◽

Nucleation And Growth ◽

Ni Alloys ◽

Melt Spun ◽

Crystal Fibers ◽

Rapidly Solidified

Large additions of B to Fe-Ni alloys can lead to the formation of an amorphous structure, if the alloy is rapidly cooled from the liquid state to room temperature. Isothermal aging of such structures at elevated temperatures causes crystallization to occur. Commonly such crystallization pro ceeds by the nucleation and growth of spherulites which are spherical crystalline bodies of radiating crystal fibers. Spherulite features were found in the present study in a rapidly solidified alloy that was fully crysstalline as-cast. This alloy was part of a program to develop an austenitic steel for elevated temperature applications by strengthening it with TiB2. The alloy contained a relatively large percentage of B, not to induce an amorphous structure, but only as a consequence of trying to obtain a large volume fracture of TiB2 in the completely processed alloy. The observation of spherulitic features in this alloy is described herein. Utilization of the large range of useful magnifications obtainable in a modern TEM, when a suitably thinned foil is available, was a key element in this analysis.

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