Influence of Copper Additions in Fe-10Ni (mass %) Alloys on Cooling Microstructures

Austenite/ferrite phase transformations in Fe-xCu-10Ni alloys, 0<x<15 (mass%), are studied under two different cooling conditions, ice-brined quenching or slow cooling in the dilatometer. The influence of copper addition and cooling rate on the microstructure of the alloys is studied. Metallographic examinations of quenched samples show that metastable transformations occur during cooling. As for Fe-Ni alloys, it is impossible to stabilize the high temperature phase (γFeNi) in the Fe-Ni-Cu alloys. Dilatometry measurements of the γ → α transformation temperature with a cooling rate of 2°C/min also indicate a metastable phase formation despite the low cooling rate. For all alloys, a mixture of massive and lath ferrite is observed, one being predominant depending on the cooling conditions and composition. It is shown that the cooling rate has nearly no influence on the microstructure of alloys with a small amount of Cu unlike the alloys containing more Cu. In all alloys containing Cu, nanometric γCu precipitates, much finer in the quenched samples, are detected in the ferrite grains.

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Correlation of Processing, Inner Structure, and Part Properties of Injection Moulded Thin-Wall Parts on Example of Polyamide 66

International Journal of Polymer Science ◽

10.1155/2014/718926 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 6

Author(s):

Dietmar Drummer ◽

Steve Meister

Keyword(s):

Cooling Rate ◽

Injection Moulding ◽

Degree Of Crystallinity ◽

Process Conditions ◽

Thin Wall ◽

Polyamide 66 ◽

Slow Cooling ◽

Cooling Conditions ◽

Internal Structures ◽

Wall Injection

In micro- and thin-wall injection moulding the process conditions affect the developed internal structures and thus the resulting part properties. This paper investigates exemplarily on polyamide 66 the interactions of different cooling conditions on the morphological and crystalline structures. The investigations reveal that a slow cooling rate of the melt results in a homogeneous morphology and a higher degree of crystallinity and also a favoured crystalline structure. Consequently, the dielectric behaviour and light transmitting part properties are affected.

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Kinetic Competition in Undercooled Liquid Alloys

MRS Proceedings ◽

10.1557/proc-398-3 ◽

1995 ◽

Vol 398 ◽

Cited By ~ 1

Author(s):

J. H. Perepezko ◽

D. R. Allen

Keyword(s):

Solid Phase ◽

Metastable Phase ◽

Rapid Quenching ◽

Kinetic Control ◽

Controlled Cooling ◽

Slow Cooling ◽

Phase Selection ◽

Nonsteady State ◽

Metastable Phase Formation ◽

Kinetic Transitions

ABSTRACTMost alloy systems can develop more than one solid phase for a given composition during solidification. For metastable undercooled liquids a thermodynamic analysis can provide insight into the range of structural and compositional options that are possible. The numerous examples of metastable phase formation during solidification of undercooled melts demonstrates that the actual phase selection is dominated by kinetics. Indeed, the observation of undercooling is linked to kinetic control. Different forms of kinetic control can be identified and include suppression of heterogeneous nucleation during slow cooling and constrained growth during rapid quenching. In both cases the kinetic competition involved in phase selection is mediated by the thermal history. Nucleation controlled kinetics can be examined in fine powders of undercooled liquids where crystallization rates and metastable phase diagrams provide a basis for analysis. Similarly, constrained growth can be examined during controlled cooling where microstructures and kinetic models can be used for analysis. The existing kinetics models appear to be adequate but the processing conditions are often dynamic and in nonsteady state conditions so that critical tests are difficult unless specific kinetic transitions are available.

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Influence of Al and N Content and Cooling Rate on the Characteristics of Complex MnS Inclusions in AHSS

Crystals ◽

10.3390/cryst10111054 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1054

Author(s):

Muhammad Nabeel ◽

Michelia Alba ◽

Neslihan Dogan

Keyword(s):

Cooling Rate ◽

High Strength Steels ◽

High Strength ◽

Slow Cooling ◽

N Content ◽

Al Content ◽

Advanced High Strength Steels ◽

Cooling Conditions ◽

Mns Precipitation ◽

Precipitation Ratio

This study focused on the characteristics of complex MnS inclusions in advanced high strength steels. The effect of metal chemistry (Al and N) and the cooling rate of steel were evaluated by analyzing the inclusions present in five laboratory produced steels. The observed complex MnS inclusions contained Al2O3-MnS, AlN-MnS, and AlON-MnS. An increase in Al content from 0.5% to 6% increased the number of complex MnS inclusions by ~4 times. In comparison, a decrease of ~80% was observed due to the increased N content of steel from <10 ppm to ~50 ppm. MnS precipitation ratio was used to determine the potency of different inclusions forming complex MnS inclusions due to heterogeneous nucleation. It was found that the MnS precipitation ratio of the observed inclusions was related to their misfit with MnS, and it decreased in the order of AlN > AlON > Al2O3. Moreover, it was determined that AlN particles could be easily engulfed at the solidification front relative to Al2O3, which resulted in a higher MnS precipitation ratio for Al2O3 under slow cooling conditions.

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A HRTEM study of metastable phase formation in Al–Mg–Cu alloys during artificial aging

Acta Materialia ◽

10.1016/j.actamat.2004.01.041 ◽

2004 ◽

Vol 52 (9) ◽

pp. 2509-2520 ◽

Cited By ~ 68

Author(s):

L. Kovarik ◽

P.I. Gouma ◽

C. Kisielowski ◽

S.A. Court ◽

M.J. Mills

Keyword(s):

Phase Formation ◽

Artificial Aging ◽

Metastable Phase ◽

Cu Alloys ◽

Metastable Phase Formation

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Towards a True Fe-Ni Phase Diagram

MRS Proceedings ◽

10.1557/proc-21-407 ◽

1982 ◽

Vol 21 ◽

Cited By ~ 5

Author(s):

P L. Rossiter ◽

R. A Jago

Keyword(s):

Phase Diagram ◽

Phase Equilibrium ◽

Phase Field ◽

Metastable Phase ◽

Equilibrium Diagram ◽

Metastable Phase Diagram ◽

Iron Meteorites ◽

Slow Cooling ◽

Ni Alloys ◽

True Equilibrium

ABSTRACTA modification to the existing Fe-Ni phase equilibrium diagram is proposed that takes account of the low-temperature ordering reaction to FeNi. It is shown that true equilibrium is never attained during slow cooling of Fe-Ni alloys, even for iron meteorites (which cool extremely slowly). In all real cases, a metastable phase diagram applies, in which the depressed γ/α+γ solvus produces a more extensive γ+ FeNi phase field than for the equilibrium case. This enlarged phase field is used to explain the decomposition of supersaturated Fe-Ni to γ+ FeNi, which is observed only in iron meteorites.

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Formation of Metastable Phases in Rapidly Quenched Binary Ti Alloys

MRS Proceedings ◽

10.1557/proc-58-353 ◽

1985 ◽

Vol 58 ◽

Author(s):

S.H. Whang ◽

C.S. Chi

Keyword(s):

Mechanical Stress ◽

Cooling Rate ◽

Phase Formation ◽

Systematic Study ◽

Metastable Phase ◽

Rapid Quenching ◽

Metastable Phases ◽

Β Phase ◽

Ti Alloys ◽

Metastable Phase Formation

ABSTRACTRapid quenching of binary Ti alloys from the melt results in various metastable phases. A systematic study has been conducted in order to elucidate principles associated with the formation of metastable phases in binary Ti alloys resulting from rapid quenching. These metastable phases that include α’, α” phases, metastable β phase, and w phase are discussed with regard to their occurrence and the extension of a phase as a function of cooling rate. Effect of cooling rate and mechanical stress applied during cooling on metastable phase formation was investigated.

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Phase Transformation and Structural Studies of EUROFER RAFM Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.514-516.500 ◽

2006 ◽

Vol 514-516 ◽

pp. 500-504 ◽

Cited By ~ 16

Author(s):

A. Paúl ◽

A. Beirante ◽

Nuno Franco ◽

Eduardo Alves ◽

José Antonio Odriozola

Keyword(s):

High Temperature Phase ◽

Temperature Phase ◽

X Ray Diffraction ◽

High Concentration ◽

Slow Cooling ◽

Austenitic Phase ◽

Full Transformation ◽

X Ray ◽

Rafm Steel

High temperature phase transformations in EUROFER reduced activation ferritic martensitic (RAFM) steel were studied in-situ by means of X-ray diffraction. Results show that, during slow cooling, the austenite to ferrite transformation takes place around 755 oC. Full transformation of the austenitic phase into pure martensite is observed for cooling above 5 oC/min. This transformation was found in samples annealed at 950 oC for 3 h and quenched in liquid nitrogen. TEM analyses reveal a high concentration of carbides along the grain boundaries of the martensitic structure. The thermal expansion coefficient derived from the measurements was 12.7x10-6 K-1.

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Optical and magnetic properties of MnBi formed directly by ion beam mixing

Journal of Materials Research ◽

10.1557/jmr.1989.1151 ◽

1989 ◽

Vol 4 (5) ◽

pp. 1151-1155 ◽

Cited By ~ 7

Author(s):

Yoshiaki Kido ◽

Masa-aki Tada

Keyword(s):

Room Temperature ◽

Metastable Phase ◽

Ion Beam ◽

Substrate Surface ◽

High Temperature Phase ◽

Temperature Phase ◽

Ion Beam Mixing ◽

Protection Effect ◽

Optical And Magnetic Properties ◽

Kinetics Of

Multilayers of Mn/Bi were irrradiated with 400 keV Xe+ at temperatures from 80 to 550 K. Ferromagnetic MnBi layers oriented perpendicular to the substrate surface were formed directly at mixing temperatures from room temperature (RT) to 500 K. The measurements of Curie point and optical Faraday rotation revealed that 60–70 at. % of MnBi ion-mixed at RT is the metastable phase (QIITP: quenched high temperature phase). The fraction of QIITP is reduced with increase in mixing temperature. It was also found that ion beam mixing yields a pronounced protection effect against the deterioration of MnBi in a moist atmosphere. A detailed discussion is given on the kinetics of ion beam mixing and the growth mechanism of the metastable MnBi grains.

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Formation of high temperature phase in flash-evaporated SnSe films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176629 ◽

1990 ◽

Vol 48 (4) ◽

pp. 698-699

Author(s):

J.P.S. Hanjra

Keyword(s):

Thin Films ◽

Electrical Properties ◽

Energy Gap ◽

Dominant Role ◽

Fine Powder ◽

High Temperature Phase ◽

Temperature Phase ◽

Water Mixture ◽

Flash Evaporation ◽

Photovoltaic Applications

Tin mono selenide (SnSe) with an energy gap of about 1 eV is a potential material for photovoltaic applications. Various authors have studied the structure, electronic and photoelectronic properties of thin films of SnSe grown by various deposition techniques. However, for practical photovoltaic junctions the electrical properties of SnSe films need improvement. We have carried out investigations into the properties of flash evaporated SnSe films. In this paper we report our results on the structure, which plays a dominant role on the electrical properties of thin films by TEM, SEM, and electron diffraction (ED).Thin films of SnSe were deposited by flash evaporation of SnSe fine powder prepared from high purity Sn and Se, onto glass, mica and KCl substrates in a vacuum of 2Ø micro Torr. A 15% HF + 2Ø% HNO3 solution was used to detach SnSe film from the glass and mica substrates whereas the film deposited on KCl substrate was floated over an ethanol water mixture by dissolution of KCl. The floating films were picked up on the grids for their EM analysis.

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