scholarly journals INFLUENCE OF COOLING RATE AND ALLOYING ELEMENTS ON THE MICROSTRUCTURE OF THE Al-Mn-BASED ALLOY

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Boštjan Markoli ◽  
Kemal Delijić ◽  
Neva Štrekelj ◽  
Iztok Naglič
Keyword(s):  
Chemical Composition ◽  
Cooling Rate ◽  
Weight Ratio ◽  
Alloy System ◽  
Specific Weight ◽  
Primary Phase ◽  
Cooling Rates ◽  
The Past ◽  
Mathematic Modeling ◽  
Methods And Techniques

Aluminum-based alloys have been used extensively for the past five decades primarily due to their good strength vs. specific weight ratio. Numerous methods and techniques have been devised to further improve mechanical properties of these alloys as they are often used in the transport applications. Influence of the cooling rate and chemical composition on the constitution of Al-Mn-based alloy has been investigated. Elements such as B, Be, C, Ca, Cu, Fe, Mg, Si, Sr and Ti have been introduced to Al-Mn alloys in order to study their influence. Changes in cooling rates during casting using permanent copper molds with different sized troughs have also been monitored. Combined influence of changes in chemical composition and cooling rates was followed using LOM, SEM, EDS, DAS measurement and mathematic modeling. It has been established that Al-Mn-based alloys form a lot of different phases during synthesis and solidification, mostly crystalline intermetallics, but also in some cases quasicrystalline (QC) ones, especially when cooling rates exceed 500 Ks-1. QCs are currently also considered as an alternative for reinforcement of Al-Mn-based alloys. It was found that in the case of alloy system Al-Mn-Cu-Be and cooling rates between 500 and 1350 Ks-1 the preferred phase formed was an icosahedral QC phase or iQC. Icosahedral QC phase formed as the primary phase and in some cases also in the form of the quasicrystalline eutectic (αAl + iQC). Additions of B, C, Ca, Ti and Sr have not proven to be effective in promoting formation of quasicrystals in cast Al-Mn alloys whilst Fe, Cu, Mg and Si proved to be highly efficient.

Features of Amorphization of the Fe-TM-Nd-REM-B Alloys System at Melt Quenching by Gas Atomization

2019 ◽  
Vol 31 ◽  
pp. 51-55
Author(s):  
Mikhail Sorokovikov ◽  
Valeriy V. Savin ◽  
Ludmila A. Savina ◽  
V.A. Chaika ◽  
I.S. Zherebcov
Keyword(s):  
Chemical Composition ◽  
Cooling Rate ◽  
Primary Crystallization ◽  
Primary Phase ◽  
Gas Atomization ◽  
Spherical Powder ◽  
Similar Chemical ◽  
Powder Particles ◽  
The Moment ◽  
Triple Eutectic

Gas atomization powders (GAP) chemical composition which corresponds to the first area of the phase equilibrium, and the fraction that ensures a cooling rate of a separate powder particle of more than 103K/s contains an amorphous component of two types: the first (AC1) has a chemical composition similar to that of the alloy; and the second (AC2) has a chemical composition of the triple eutectic. AC1 is mostly localized on the surface of the powder particles (in the form of layers, shells, nodules) or are detected in the whole volume of the spherical powder particles with its size less than 5 μm. The authors hold that during gas atomization, powder particles of this size have a cooling rate ≥ 105 K/s. Alloys having a similar chemical composition at similar cooling rates are also amorphized by quenching from the liquid state. This proves that an amorphous alloy of the first type is formed directly from a supercooled melt. While AC2 (enriched by Nd) is formed on the border or in the between the crystal phase Fe14Nd2B of the remaining (after primary crystallization during the primary phase) melt enriched by the moment of the solidification of Nd.

Kinetics and Mechanisms of Formation of Al-Ni Intermetallics

1986 ◽  
Vol 81 ◽  
Author(s):  
J. A. Patchett ◽  
G. J. Abbaschian
Keyword(s):  
Cooling Rate ◽  
Nucleation And Growth ◽  
Primary Phase ◽  
Peritectic Temperature ◽  
Cooling Rates ◽  
Fault Density ◽  
Metastable Extension ◽  
Mechanisms Of Formation ◽  
Free Growth ◽  
Kinetics Of

AbstractThe effects of cooling rate and composition on the nucleation and growth kinetics of NiAl, Ni2Al3, and NiAl3 intermetallics were studied for alloys containing 25 and 31.5 ht.% Ni. Fgr the former composition, the peritectic regction Ni Al + Liquid → NiAl3 was studied over cooling rates from 20 to 105 K/s. For the latter composhtion, the reaction NiAl + Liquid → Ni2Al3 was studied at cooling rates ranging form 10 to 600 K/sec. The amounis of constituent phases are shown to depend on the cooling rate, and for the peritectic phases, on the surface area of the primary phase. The nucleation of Ni2Al3 and NiAl3, and the ordering of the aluminum-rich NiAl were also examines uding trans ission electron microscopy. Cooling the NiAl + liquid below the peritectic temperature results in a metastable extension of NiAl with a high dislocation and stacking fault density, followed by the epitaxial nucleation and almost dislocation-free growth of Ni2Al3 In contrast, the nucleation of the NiAl3 on Ni2Al3 occurs directly witgoud the formationof an intermediate region.

Improvement of Mechanical Properties of Fe-Cr-Mo-[Cu-Ni]-C Sintered Sintered Steels by Sinter Hardening

2011 ◽  
Vol 672 ◽  
pp. 31-38 ◽  
Author(s):  
Eva Dudrová ◽  
Marco Actis Grande ◽  
Mario Rosso ◽  
Margita Kabátová ◽  
Róbert Bidulský ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Chemical Composition ◽  
Cooling Rate ◽  
Impact Energy ◽  
Vacuum Sintering ◽  
Cooling Rates ◽  
Sintered Steels ◽  
Conventional Sintering

The effect of high temperature sintering and high cooling rate on shifting the microstructural composition to the favourably of martensite-bainite structures and thus effective improvement of mechanical properties of sintered steels based on Astaloy CrL powder with an addition of 1 and 2% Cu or 50% Distaloy AB powder and 0.65% C was investigated. All the systems were processed by both sinter-hardening and conventional sintering. The vacuum sintering at high-temperature of 1240 0C and at common temperature of 1180 0C were integrated with high (6 0C/s), medium (3 0C/s) and slow (0.1 0C/s) cooling rates; conventional sintering at 1180 0C with cooling rate of ~0.17 0C/s was carried out in a N2+10%H2 atmosphere. In dependence on chemical composition, the yield and tensile strengths of 890-1150 MPa and 913-1230 MPa respectively and impact energy of 10-15 J were achieved by sinter-hardening. The yield and tensile strengths are approximately double than those resulting from conventional sintering.

scholarly journals Sakurai’s Object: Constraints from its Variability?

1998 ◽  
Vol 11 (1) ◽  
pp. 360-360
Author(s):  
T. Gautschy ◽  
H.W. Duerbeck ◽  
A.M. Van Genderen ◽  
S. Benetti
Keyword(s):  
Cooling Rate ◽  
Nuclear Energy ◽  
Stability Analyses ◽  
The Past ◽  
Stellar Pulsations ◽  
First Results ◽  
Effective Temperatures ◽  
Stellar Envelopes ◽  
Light Variability ◽  
Hr Diagram

The peculiar outburst of the star baptized Sakurai’s Object (SO) is a conceivable example of a late He shell flash in a post-AGB object. The new source of nuclear energy forces such objects toward high luminosities and eventually low effective temperatures; they cross the HR diagram in a comparable fashion as FG Sge did in the past - i.e., they move noticeably on the HR diagram on human timescales. From monitoring campaigns of SO during the last year, first estimates of its cooling rate were derived and in particular cyclic light variability was established. We present first results from attempts to model stellar envelopes appropriate for SO. As we hypothesize the light variability to be attributable to stellar pulsations, we aim at constraining the basic stellar parameters based on stability analyses of our envelope models. Radial, nonadiabatic stability computations provided predictions of the modal content which should be observable as SO evolves. The particular components in such mode spectra of SO as they are to appear in the coming years should indeed help to constrain basic stellar parameters such as mass and luminosity.

The effect of cooling rate on crystallization behavior and tensile properties of CF/PEEK composites

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guangming Dai ◽  
Lihua Zhan ◽  
Chenglong Guan ◽  
Minghui Huang
Keyword(s):  
Cooling Rate ◽  
Crystallization Temperature ◽  
Crystallization Behavior ◽  
Crystalline Polymer ◽  
Scanning Calorimetry ◽  
Nonisothermal Crystallization ◽  
Cooling Rates ◽  
Control Range ◽  
Temperature Range ◽  
Transverse Tensile

Abstract In this study, the differential scanning calorimetry (DSC) tests were performed to measure the nonisothermal crystallization behavior of carbon fiber reinforced polyether ether ketone (CF/PEEK) composites under different cooling rates. The characteristic parameters of crystallization were obtained, and the nonisothermal crystallization model was established. The crystallization temperature range of the material at different cooling rates was predicted by the model. The unidirectional laminates were fabricated at different cooling rates in the crystallization temperature range. The results showed that the crystallization temperature range shifted to a lower temperature with the increase of cooling rate, the established nonisothermal crystallization model was consistent with the DSC test results. It is feasible to shorten the cooling control range from the whole process to the crystallization range. The crystallinity and transverse tensile strength declined significantly with the increase of the cooling rate in the crystallization temperature range. The research results provided theoretical support for the selection of cooling conditions and temperature control range, which could be applied to the thermoforming process of semi-crystalline polymer matrixed composites to improve the manufacturing efficiency.

Thermal Parameters, Microstructure and Porosity During Transient Solidification of Ternary Al–Cu–Si Alloys

2012 ◽  
Vol 730-732 ◽  
pp. 883-888 ◽  
Author(s):  
Daniel J. Moutinho ◽  
Laércio G. Gomes ◽  
Otávio L. Rocha ◽  
Ivaldo L. Ferreira ◽  
Amauri Garcia
Keyword(s):  
Growth Rate ◽  
Chemical Composition ◽  
Cooling Rate ◽  
Tip Growth ◽  
Thermal Parameters ◽  
Volumetric Fraction ◽  
Dendritic Network ◽  
Intermetallic Particles ◽  
Casting Length

Solidification of ternary Al-Cu-Si alloys begins with the development of a complex dendritic network typified by primary (λ1) and secondary (λ2) dendrite arm spacings which depend on the chemical composition of the alloy and on the casting thermal parameters such as the growth rate and the cooling rate. These thermal parameters control the scale of dendritic arms, the size and distribution of porosity and intermetallic particles in the casting. In this paper, λ1and λ2were correlated with experimental thermal parameters i.e., the tip growth rate and the tip cooling rate. The porosity profile along the casting length has also been experimentally determined. The volumetric fraction of pores increase with the increase in alloying Si and with the increase in Fe concentration at the regions close to the casting cooled surface.

Effects of RE on Critical Cooling Rate of Bearing-B Steel

2012 ◽  
Vol 535-537 ◽  
pp. 761-763 ◽  
Author(s):  
Yi Sheng Zhao ◽  
Xin Ming Zhang ◽  
Zhi Guo Gao
Keyword(s):  
Phase Change ◽  
Cooling Rate ◽  
Experimental Results ◽  
Cooling Rates ◽  
Critical Cooling Rate ◽  
The Law

The law of phase change of bearing-B steel during continual cooling was studied by adopting dilatometer. The CCT curves of bearing-B steel were drawn, and the effects of RE on critical cooling rates were studied. The experimental results show that the start temperatures of martensite TM was decreased from 438 to 404°C. The critical cooling rate was simultaneously decreased from 33 to 15°C/s.

Effects of the Cooling Rate on the Acoustic Properties of Pb-10Sn Solder

2012 ◽  
Vol 729 ◽  
pp. 356-360
Author(s):  
Endre Harkai ◽  
Tamás Hurtony ◽  
Péter Gordon
Keyword(s):  
Sound Velocity ◽  
Cooling Rate ◽  
Acoustic Microscopy ◽  
Acoustic Properties ◽  
Scanning Acoustic Microscopy ◽  
Cooling Rates ◽  
Reliability Parameters ◽  
Microscopy Characterization ◽  
The Given

Microhardness and sound velocity were measured in case of differently prepared solder samples. The used Pb-10Sn solder samples were melted then cooled down applying different cooling rates. These procedures caused variant microstructure thus different microhardness and sound velocity values. The sound velocity was measured by means of scanning acoustic microscopy. Characterization of solder materials by acoustic microscopy gives the possibility to non-destructively estimate mechanical and reliability parameters of the given material.

The effect of various cooling rates on the membrane ultrastructure of frozen human erythrocytes and its relation to the extent of haemolysis after thawing

1981 ◽  
Vol 49 (1) ◽  
pp. 369-382
Author(s):  
S. Fujikawa
Keyword(s):  
Cooling Rate ◽  
Human Erythrocytes ◽  
Ice Crystals ◽  
Erythrocyte Membranes ◽  
Ultrastructural Changes ◽  
Cooling Rates ◽  
Intracellular Ice ◽  
Frozen State ◽  
Membrane Ultrastructure ◽  
Fast Freezing

Human erythrocytes suspended in buffered isotonic saline were frozen to the temperature of liquid nitrogen at various cooling rates of 3, 140, 700, 1800, 3500, 8000 and 11 500 deg. C/min. The membrane ultrastructure in the frozen state and the extent of haemolysis after thawing were examined at each cooling rate. As the cooling rates increased from 3 to 3500 deg. C/min, the extent of lysis gradually decreased, but further increase in cooling rates in excess of 8000 deg. C/min resulted in an abrupt increase of lysis. Membrane-associated vesicles devoid of intramembrane particles (IMPs) were formed in the erythrocyte membranes frozen at cooling rates slower than 1800 deg. C/min. The frequency and size of these vesicles were highly cooling-rate-dependent and they were no longer formed in the erythrocyte membranes frozen at cooling rates faster than 3500 deg. C/min. Another membrane ultrastructural change associated closely with the formation of intracellular ice crystals appeared at cooling rates faster than 8000 deg. C/min. The membrane regions in direct contact with intracellular ice crystals were physically damaged and had an appearance resembling worm-eaten spots. The erythrocytes frozen at a cooling rate of 3500 deg. C/min exhibited ultrastructural integrity of the membrane by avoiding the membrane changes caused by either slow or fast freezing. It is suggested, from the close relation between membrane ultrastructure and the extent of haemolysis, that the ultrastructural integrity of membrane in the frozen state is important for avoiding haemolysis after thawing, and that the membrane ultrastructural changes caused by both slow and fast freezing were responsible for the lysis after thawing.

Phase Selection in Sub-Rapidly Solidified Au-20Sn Alloys

2015 ◽  
Vol 817 ◽  
pp. 325-330
Author(s):  
Yu Hai Qu ◽  
Kai Jin Yang ◽  
Yan Tian Zhou ◽  
Yong Mao ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Copper Mold ◽  
Cooling Rates ◽  
Phase Selection ◽  
Graphite Mold ◽  
Injection Casting ◽  
Rapidly Solidified ◽  
Ausn Phase

The sub-rapidly solidified Au-20Sn eutectic alloys were prepared by four different solidification pathways, such as, graphite mold conventional casting, graphite mold injection casting, copper mold injection casting, and water-cooled copper mold suction casting. The precipitating sequences of competing primary phases of sub-rapidly solidified Au-20Sn alloys with four different cooling rates were investigated. The results show that phase selection process is related to the cooling rates during sub-rapid solidification process. The primary ζ'-Au5Sn phase with developed dendrites precipitate at low cooling rate (2.4×10−4.2×102K/min) and the morphologies of the primary ζ'-Au5Sn change to rosette-like at higher cooling rate (9.0×103K/min). While the cooling rate reaches to 3.5×104K/min, the primary ζ'-Au5Sn phase can be suppressed but δ-AuSn phase will precipitate prior to the ζ'-Au5Sn phase. On the basis of the classical nucleation theory and transient nucleation theory, the process of competitive nucleation between the ζ'-Au5Sn phase and the δ-AuSn phase were analyzed for sub-rapid solidified Au-20Sn alloy. The theoretical calculations are consistent with the experimental investigations.

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