Irregular growth of the γ′ phase in a Ni-based superalloys under slow cooling rate

2021 ◽  
pp. 131067
Author(s):  
Hao Yu ◽  
Zhaotian Wang ◽  
Baoyun Zhang ◽  
Yongquan Ning ◽  
M.W. Fu
Keyword(s):  
Cooling Rate ◽  
Slow Cooling ◽  
Irregular Growth

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

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
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.

Enhancing the electrical conductivity of PP/CNT nanocomposites through crystal-induced volume exclusion effect with a slow cooling rate

2020 ◽  
Vol 183 ◽  
pp. 107663 ◽  
Author(s):  
Jun Wang ◽  
Yasamin Kazemi ◽  
Sai Wang ◽  
Mahdi Hamidinejad ◽  
Mayesha B. Mahmud ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Cooling Rate ◽  
Slow Cooling ◽  
Exclusion Effect

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

Crystals ◽  
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.

40Ar/39Ar and K–Ar age constraints on shear zone evolution, southern Taltson magmatic zone, northeastern Alberta

1995 ◽  
Vol 32 (3) ◽  
pp. 281-291 ◽  
Author(s):  
H. E. Plint ◽  
M. R. McDonough
Keyword(s):  
Cooling Rate ◽  
Shear Zone ◽  
High Grade ◽  
Slow Cooling ◽  
Rapid Cooling ◽  
Deformational History ◽  
The Mean ◽  
Exhumation Rates ◽  
Northeastern Alberta ◽  
Age Constraints

New 40Ar/39Ar analyses of hornblende, muscovite, biotite, and K-feldspar constrain the timing of deformation and cooling of the southern Taltson magmatic zone, which underwent lower granulite to upper amphibolite grade deformation, in part synchronous with voluminous 1.99–1.92 Ga magmatism. New data are combined with existing K–Ar dates into a regional cooling framework to provide thermotemporal constraints on the deformational history. 40Ar/39Ar hornblende ages of ca. 1900 Ma are interpreted to record relatively rapid cooling following ductile thrusting on the Andrew Lake shear zone, and younger anatectic magmatism. These data, with published K–Ar and U–Pb data, support relatively rapid cooling of the Taltson magmatic zone from monazite closure temperature of 725 °C at ca. 1930 Ma to 525 °C at ca. 1900 Ma. Cooling rate estimates are about 7 °C/Ma, which suggests moderate exhumation rates during the high-grade part of the deformational history. A muscovite 40Ar/39Ar plateau age of 1803 ± 11 Ma is consistent with the mean muscovite K–Ar age of 1792 Ma, indicating regional cooling through about 350 °C at ca. 1800 Ma. 40Ar/39Ar ages from magmatic biotite of 1856 and 1799 Ma also suggest slow cooling during greenschist grade deformation, which can be no older than ca. 1860 Ma. A K-feldspar 40Ar/39Ar age of 1681 Ma provides a lower limit for the time of greenschist grade deformation. Cooling rate estimates during amphibolite to greenschist grade deformation are 1.75–2.25 °C/Ma.

Quench Brittleness of 12%Cr Martensitic Heat-Resistant Steel

2011 ◽  
Vol 479 ◽  
pp. 8-12 ◽  
Author(s):  
Gang Yang ◽  
Zheng Dong Liu ◽  
Shi Chang Cheng ◽  
Mu Xin Yang
Keyword(s):  
Impact Toughness ◽  
Cooling Rate ◽  
Microstructural Characterization ◽  
Temper Brittleness ◽  
Resistant Steel ◽  
Slow Cooling ◽  
Continuous Precipitation ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
The Impact

The mechanism of brittleness due to slow cooling during quenching was experimentally investigated in 12% Cr martensitic heat resistant steel. The mechanical property tests and microstructural characterization by SEM、TEM and XRD were conducted. The results showed the impact toughness would decrease with the slowing of cooling rate during quenching, and the low cooling rate within the temperature range from 820 to 660 °C played a significant effect on the impact toughness . Different from the mechanism of temper brittleness, the main causes of embrittlement due to the slow cooling upon quenching were both the continuous precipitation of M23C6 along prior austenite grain boundaries during the process of slow cooling and that of M2C along prior residual austenite film during tempering, and this kind of quench brittleness was nonreversal.

Connectivity and flux pinning improvements in Ag-clad BSCCO-2223 tapes produced by changes in the cooling rate

1997 ◽  
Vol 12 (11) ◽  
pp. 2997-3008 ◽  
Author(s):  
J. A. Parrell ◽  
D. C. Larbalestier ◽  
G. N. Riley ◽  
Q. Li ◽  
W. L. Carter ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Critical Temperature ◽  
Cooling Rate ◽  
Flux Pinning ◽  
Irreversibility Field ◽  
Superconducting Properties ◽  
Temperature Transition ◽  
Slow Cooling ◽  
Reaction Heat ◽  
Final Reaction

The rate at which Ag-clad (Bi, Pb)2Sr2Ca2Cu3Ox tapes are cooled from their final reaction heat treatment influences both the intergranular connectivity and intragranular flux pinning strength of the polycrystalline filaments. As the cooling rate from 825 °C to 730 °C in 7.5% O2 was decreased over a range of 5 °C/min to 0.005 °C/min, Jc (77 K, 0 T) increased from ∼8 to ∼24 kA/cm2, and the irreversibility field increased from, ∼120 to, ∼200 mT. The Jc (4.2 K, 0 T) increased in a similar fashion. Cooling slowly also sharpened the critical temperature transition and increased the critical onset temperature from 107 K to 109 K. These improvements in the superconducting properties occurred despite partial decomposition of the (Bi, Pb)2Sr2Ca2Cu3Ox phase into non-superconducting impurity phases during the slow cooling. A microstructural basis for these multiple effects is described.

Effect of sintering temperature and cooling rate on microstructure, phase formation, and critical current density of Ag-sheathed Bi1.8Pb0.4Sr2Ca2Cu3Ox superconducting tapes

1998 ◽  
Vol 13 (2) ◽  
pp. 261-268 ◽  
Author(s):  
J. P. Singh ◽  
N. Vasanthamohan
Keyword(s):  
Critical Current Density ◽  
Cooling Rate ◽  
Critical Current ◽  
Current Density ◽  
Sintering Temperature ◽  
Superconducting Tapes ◽  
Temperature Quenching ◽  
Slow Cooling ◽  
Higher Temperature ◽  
Powder In Tube

Silver-sheathed Bi–Pb–Sr–Ca–Cu–O (2223) superconducting tapes (with a starting composition of Bi1.8Pb0.4Sr2Ca1Cu2O8, calcium cuprate, and CuO) were fabricated by the powder-in-tube technique. The tapes were sintered at various temperatures to optimize the formation of Bi1.8Pb0.4Sr2Ca2Cu3O10 phase within the tape. The results show that sintering within the temperature range of 815–825 °C can produce tapes with high critical current density (Jc). The Jc of samples sintered at the higher temperature of 825 °C, where more liquid is present, depended markedly on the rate at which tapes were cooled from the sintering temperature; samples sintered at lower temperatures did not exhibit such a cooling-rate effect. The optimum combination of phase purity and microstructure that yielded an average transport Jc of ≥ 2.5 × 104 A/cm2 was obtained when the tapes were sintered at 825 °C for 150 h and cooled at a rate of 25 °C/h from the sintering temperature. Quenching studies indicate that the Bi-2223 phase becomes unstable below 700 °C during slow cooling. This result may have important implications for processing Bi–Sr–Ca–Cu–O tapes with high Jc. Addition of 15 vol.% Ag flakes to the monolithic core exerted no significant effect on Jc.

scholarly journals Thermal stress, cooling-rate and fictive temperature of silicate melts

2021 ◽  
Vol 176 (10) ◽  
Author(s):  
Sharon L. Webb
Keyword(s):  
Heat Capacity ◽  
Cooling Rate ◽  
Heating Rate ◽  
Calibration Curve ◽  
Silicate Melts ◽  
Internal Stresses ◽  
Heating Rates ◽  
Fictive Temperature ◽  
Slow Cooling ◽  
Cooling Rates

AbstractThe unknown cooling-rate history of natural silicate melts can be investigated using differential scanning heat capacity measurements together with the limiting fictive temperature analysis calculation. There are a range of processes occurring during cooling and re-heating of natural samples which influence the calculation of the limiting fictive temperature and, therefore, the calculated cooling-rate of the sample. These processes occur at the extremes of slow cooling and fast quenching. The annealing of a sample at a temperature below the glass transition temperature upon cooling results in the subsequent determination of cooling-rates which are up to orders of magnitude too low. In contrast, the internal stresses associated with the faster cooling of obsidian in air result in an added exothermic signal in the heat capacity trace which results in an overestimation of cooling-rate. To calculate cooling-rate of glass using the fictive temperature method, it is necessary to create a calibration curve determined using known cooling- and heating-rates. The calculated unknown cooling-rate of the sample is affected by the magnitude of mismatch between the original cooling-rate and the laboratory heating-rate when using the matched cooling-/heating-rate method to derive a fictive temperature/cooling-rate calibration curve. Cooling-rates slower than the laboratory heating-rate will be overestimated, while cooling-rates faster than the laboratory heating-rate are underestimated. Each of these sources of error in the calculation of cooling-rate of glass materials—annealing, stress release and matched cooling/heating-rate calibration—can affect the calculated cooling-rate by factor of 10 or more.

scholarly journals Solidification and Segregation Behaviors of Superalloy IN718 at a Slow Cooling Rate

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2398 ◽  
Author(s):  
Xiao Shi ◽  
Shengchao Duan ◽  
Wensheng Yang ◽  
Hanjie Guo ◽  
Jing Guo
Keyword(s):  
Cooling Rate ◽  
Gas Turbines ◽  
Solid Phase ◽  
Liquid Fraction ◽  
Liquid Density ◽  
Slow Cooling ◽  
Negative Segregation ◽  
Different Temperatures ◽  
Industrial Gas Turbines ◽  
Rate Characteristic

The solidification and micro- and macro-segregation behaviors of as-cast INCONEL 718 (IN718) alloy at different temperatures under a slow cooling rate (5 °C/min) were investigated in this study. The results indicate that the solid-liquid interface grows into reticulation of hexagons during solidification. The variation trend of the solid fraction and transition rate of the solid phase with solidification time can be well characterized by the Boltzmann and Gaussian distribution, respectively. The order of segregation degree of negative segregation elements is: Fe > Cr > Al. Nb is the most principal positive segregation element, which is abundant in the long-term unsolidified remaining liquid. At the terminal stage of solidification, the increasing tendencies of the Nb and Mo contents in the liquid and the residual liquid density with decreasing temperature reverse due to the formation of the Laves phase. The freckles are most likely to form in the early stages of solidification, at which the liquid fraction is between 0.3 and 0.2, and the temperature range is about 1320 °C to 1310 °C. The information produced is expected to characterize the solidification and segregation behaviors of IN718 alloy when cooled at a slow rate characteristic of larger ingots typical of those required for industrial gas turbines and aircraft engines.

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