scholarly journals Microstructure, hardness and interfacial energy in Co-9Al-10W-xNi (x=15, 25, 35 at. %) alloys during aging

2017 ◽  
Vol 53 (3) ◽  
pp. 303-308 ◽  
Author(s):  
C. Che ◽  
S. Yang ◽  
M. Wei ◽  
L. Zhang ◽  
Q. Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Interfacial Energy ◽  
Aging Temperature ◽  
Volume Fraction ◽  
Ni Alloys ◽  
Interfacial Energies ◽  
Ni Content ◽  
Coarsening Kinetics ◽  
The Relationship ◽  
Kinetics Of

In the present paper, three Co-Al-W-Ni alloys (i.e., Co-9Al-10W-xNi with x=15, 25, 35 at. %) and their heat treatment mechanisms were carefully designed on the basis of the available phase equilibrium information. The temporal evolution of the microstructure and hardness in the Co-9Al-10W-xNi (x=15, 25, 35) alloys during aging process was measured, from which the effect of additional Ni contents, aging temperature and time on microstructure and hardness in the three Co-Al- W-Ni alloys was analyzed. Considering that the alloy compositions and heat treatment are not directly related with the hardness, the relationship between hardness and microstructure was then linked. It was found that the hardness of Co-based superalloys increases as the volume fraction of ?' precipitates increases, while decreases with the increase of the radius and interval of ?' precipitates. Moreover, the interfacial energy of ?/?' interface was also evaluated on the basis of the coarsening kinetics of ?' precipitates and the Philippe-Voorhees model in combination with the thermodynamic and atomic mobility databases. The results indicate that the interfacial energies of ?/?' interface reduce as the increase of additional Ni content and aging temperature.

scholarly journals Optimization of Interfacial Energy for Langer-Schwartz Based Precipitation Simulations

2021 ◽  
Author(s):  
Conner Sarich ◽  
Adam Hope ◽  
Jim Rule
Keyword(s):  
Experimental Data ◽  
Interfacial Energy ◽  
Volume Fraction ◽  
Published Data ◽  
Low Alloy Steels ◽  
Interfacial Energies ◽  
Nucleation Sites ◽  
Alloy Steels ◽  
Thermal Histories ◽  
Al 2024

Abstract Precipitation kinetics were investigated in select Fe, Ni, and Al alloys using a CALPHAD based precipitation model based on Langer-Schwartz theory. Thermodynamic and kinetic data are taken from commercially available CALPHAD software, but reliable interfacial energy data for precipitates needed for the calculations is often lacking. While models exist to approximate these interfacial energies, this study has focused on deriving more reliable estimates by comparison with experimental data. By performing simulations with thermal histories, nucleation sites, and precipitate morphologies that closely replicate experimental data found in literature, the interfacial energies were optimized until volume fraction and mean radius values closely matched the published data. Using this technique, interfacial energy values have been determined for carbides in Grade 22 low alloy steels, delta phase in Ni 625 and 718, SPhase in Al 2024, and Q’ and β’’ in Al 6111, and can be used for future predictive precipitation simulations.

Influence of Heat Treatment on γ´ Phase and Property of a Directionally Solidified Superalloy

2018 ◽  
Vol 37 (3) ◽  
pp. 271-276
Author(s):  
P. C. Xia ◽  
K. Xie ◽  
H. Z. Cui ◽  
J. J. Yu
Keyword(s):  
Heat Treatment ◽  
Aging Temperature ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
Nickel Base Superalloy ◽  
Directionally Solidified ◽  
Stress Rupture Life ◽  
Stress Rupture Property ◽  
Nickel Base

AbstractThe effects of heat treatment process on microstructure and properties of a nickel base superalloy are investigated. The size of γ´ phase decreases and the stress rupture life of alloy at 1100 °C/60 MPa drops with the rise of cooling rate. The hardness at room temperature also increases. The size of cuboidal γ´ precipitate and the volume of spherical γ´ precipitate increase with the rise of aging temperature. With higher aging temperature, the alloy exhibits bimodal γ´ phase. A reasonable combination of the size and volume fraction of cuboidal and spherical γ´ phase can obtain better stress rupture property at 1100 °C/60 MPa.

Relation between oxidation/crystallization and degassing upon reheating of basalt glass from Kilauea, Hawaii

2005 ◽  
Vol 69 (2) ◽  
pp. 103-117 ◽  
Author(s):  
D. J. M. Burkhard
Keyword(s):  
Heat Treatment ◽  
Convincing Evidence ◽  
Oxidation Products ◽  
Isothermal Heat Treatment ◽  
Scanning Calorimetry ◽  
Evolved Gas ◽  
Basalt Glass ◽  
Controlled Crystallization ◽  
The Relationship ◽  
Kinetics Of

AbstractBasalt glass from Kilauea, Hawaii (SBG) starts to crystallize upon heat treatment in air at ∽840°C. In addition, oxidation takes place. The kinetics of both processes may be readily quantified though the mechanism is difficult to access. This work investigates the relationship between these processes, crystallization and oxidation, and the escape of volatiles from the glass/liquid upon reheating. Evolved gas analyses and differential scanning calorimetry are the techniques used. In addition, isothermal heat treatment in argon is carried out in order to eliminate the external reason for oxidation, the oxygen gradient, and to focus on intrinsic oxidation. Products are examined with 57Fe Mössbauer spectroscopy. As expected, degassing temperatures of SBG, and of two MORB samples, considered for comparison, are above the glass transition temperature. We find no convincing evidence of intrinsic oxidation. Degassing is likely to induce interface-controlled crystallization.

Interaction of the Precipitation Kinetics of δ And γ’ Phases in Nickel-Base Superalloy ATI Allvac® 718PlusTM

2010 ◽  
Vol 638-642 ◽  
pp. 2712-2717 ◽  
Author(s):  
Rene Radis ◽  
Gerald A. Zickler ◽  
Martin Stockinger ◽  
Christof Sommitsch ◽  
Ernst Kozeschnik
Keyword(s):  
Volume Fraction ◽  
Diffuse Interface ◽  
Nickel Base Superalloy ◽  
Interfacial Energies ◽  
Precipitation Behaviour ◽  
Planar Phase ◽  
Nickel Base ◽  
Kinetics Of ◽  
Entropic Effects ◽  
Base Superalloy

In this paper, the precipitation behaviour of  (Ni3(Nb,Al)) and ’ (Ni3(Al,Ti,Nb)) phases in the nickel-base superalloy ATI Allvac® 718PlusTM, as well as their kinetic interactions are discussed. Important parameters such as volume fraction, mean radius and number density of precipitates are experimentally determined and numerically simulated as a function of the heat treatment parameters time and temperature. To match the experimentally observed kinetics, the predicted interfacial energy of the precipitates, as calculated for a sharp, planar phase boundary, is adjusted to take into account the interfacial curvature and entropic effects of a diffuse interface. Correction functions for the interfacial energies of  as well as ’ precipitates are presented. Using these modified interfacial energies, the calculated results show excellent agreement with the experimental measurements.

Influence of Mn Additions on the Thermoelastic and Pseudoelastic Behaviour of Cu-Ai-Ni Alloys

1994 ◽  
Vol 360 ◽  
Author(s):  
M.A. Morris ◽  
T. Lipe
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Activation Energies ◽  
Manganese Concentration ◽  
Ni Alloys ◽  
Two Phases ◽  
Mn Additions ◽  
Kinetics Of

AbstractThe transformation properties of Cu-Al-Ni alloys modified by the additions of boron and manganese have been interpreted by studying the reversibility and stability of the martensitic transformation as a function of heat treatment and of manganese concentration between 2 and 4 wt%. The alloy containing 2% Mn exhibits a lack of thermoelasticity due to a decrease of the degree of B2 order and supression of DO3 order during quenching and the increase of both types of order during annealing. From the determination of the activation energies responsible for the martensitic and reverse transformations, we have deduced that, in both cases, the kinetics of the transformation are controlled by an atomic jump at the interface between the two phases.

scholarly journals Effect of Post-weld Heat Treatment on Microstructures and Properties of Laser-Welded FV520B Steel

2020 ◽  
Author(s):  
Dewei Deng ◽  
LV Jie ◽  
MA Yushan ◽  
TIAN Xin ◽  
HUANG Zhiye ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Impact Toughness ◽  
Aging Time ◽  
Vickers Hardness ◽  
Aging Temperature ◽  
Volume Fraction ◽  
Aging Treatment ◽  
Strengthening Effect ◽  
Low Carbon ◽  
Reversed Austenite

Abstract For the laser-welded FV520B steel welds, the experiments of post-weld aging treatment have been conducted at different temperatures. The microstructural transformations under various heat-treatment conditions are investigated by optical microscopy (OM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Vickers hardness and impact toughness are also measured after the aging treatments. The results of microstructural observations show that before heat treatment the fusion zone (FZ) mainly includes low carbon martensite and δ-ferrite. With the increase of aging temperature and time, in FZ the δ-ferrite phase spheroidizes and disappears. When the aging temperature is lower than 400 ºC, the carbides grow with increasing aging time. After aging treatment at 550 ºC for 12 h, a small amount of reversed austenite appears in FZ. The volume fraction of reversed austenite increases with the further increase of aging temperature and time. However, in FZ all the reversed austenite disappears after aging at 650 ºC for 12 h. This indicates that at room temperature the amount of reversed austenite is related not only to the volume fraction of the reversed austenite obtained from aging, but also to the stability of reversed austenite during cooling. The Vickers hardness and impact toughness of the welds mainly depend on the balance between the dispersion strengthening effect of the Cu-rich precipitates and the weakening effect of tempered martensite. The presence of reversed austenite can also improve the toughness of welds. In addition, as the aging temperature and aging time increase, the hardness difference between the three zones of FZ, heat affected zone (HAZ) and base metal (BM) decreases.

Vanadium Additions to a High-Cr White Iron and its Effects on the Abrasive Wear Behavior.

MRS Advances ◽  
2020 ◽  
Vol 5 (59-60) ◽  
pp. 3077-3089
Author(s):  
Alexeis Sánchez ◽  
Arnoldo Bedolla-Jacuinde ◽  
Francisco V. Guerra ◽  
I. Mejía
Keyword(s):  
Heat Treatment ◽  
Abrasive Wear ◽  
Volume Fraction ◽  
Wear Behavior ◽  
Wear Behaviour ◽  
White Iron ◽  
Heat Treated ◽  
Bulk Hardness ◽  
Abrasive Wear Behavior ◽  
Vanadium Carbides

AbstractFrom the present study, vanadium additions up to 6.4% were added to a 14%Cr-3%C white iron, and the effect on the microstructure, hardness and abrasive wear were analysed. The experimental irons were melted in an open induction furnace and cast into sand moulds to obtain bars of 18, 25, and 37 mm thickness. The alloys were characterized by optical and electronic microscopy, and X-ray diffraction. Bulk hardness was measured in the as-cast conditions and after a destabilization heat treatment at 900°C for 45 min. Abrasive wear resistance tests were undertaken for the different irons according to the ASTM G65 standard in both as-cast and heat-treated conditions under a load of 60 N for 1500 m. The results show that, vanadium additions caused a decrease in the carbon content in the alloy and that some carbon is also consumed by forming primary vanadium carbides; thus, decreasing the eutectic M7C3 carbide volume fraction (CVF) from 30% for the base iron to 20% for the iron with 6.4%V;but overall CVF content (M7C3 + VC) is constant at 30%. Wear behaviour was better for the heat-treated alloys and mainly for the 6.4%V iron. Such a behaviour is discussed in terms of the CVF, the amount of vanadium carbides, the amount of martensite/austenite in matrix and the amount of secondary carbides precipitated during the destabilization heat treatment.

scholarly journals Continuous Cooling Transformation Behaviour and Bainite Transformation Kinetics of 23CrNi3Mo Carburised Steel

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 48
Author(s):  
Wenjun Song ◽  
Min Lei ◽  
Mingpan Wan ◽  
Chaowen Huang
Keyword(s):  
Phase Transformation ◽  
Volume Fraction ◽  
Austenite Formation ◽  
Steel Matrix ◽  
Transformation Kinetics ◽  
Bainite Transformation ◽  
Continuous Cooling ◽  
The Matrix ◽  
Dimensional Growth ◽  
Kinetics Of

In this study, the phase transformation behaviour of the carburised layer and the matrix of 23CrNi3Mo steel was comparatively investigated by constructing continuous cooling transformation (CCT) diagram, determining the volume fraction of retained austenite (RA) and plotting dilatometric curves. The results indicated that Austenite formation start temperature (Ac1) and Austenite formation finish temperature (Ac3) of the carburised layer decreased compared to the matrix, and the critical cooling rate (0.05 °C/s) of martensite transformation is significantly lower than that (0.8 °C/s) of the matrix. The main products of phase transformation in both the carburised layer and the matrix were martensite and bainite microstructures. Moreover, an increase in carbon content resulted in the formation of lamellar martensite in the carburised layer, whereas the martensite in the matrix was still lath. Furthermore, the volume fraction of RA in the carburised layer was higher than that in the matrix. Moreover, the bainite transformation kinetics of the 23CrNi3Mo steel matrix during the continuous cooling process indicated that the mian mechanism of bainite transformation of the 23CrNi3Mo steel matrix is two-dimensional growth and one-dimensional growth.

scholarly journals Heat Treatment Evaluation for the Camshafts Production of ADI Low Alloyed with Vanadium

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1036
Author(s):  
Eduardo Colin García ◽  
Alejandro Cruz Ramírez ◽  
Guillermo Reyes Castellanos ◽  
José Federico Chávez Alcalá ◽  
Jaime Téllez Ramírez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Ductile Iron ◽  
Volume Fraction ◽  
Energy Impact ◽  
Treatment Conditions ◽  
Mold Casting ◽  
Grade 3 ◽  
Good Agreement

Ductile iron camshafts low alloyed with 0.2 and 0.3 wt % vanadium were produced by one of the largest manufacturers of the ductile iron camshafts in México “ARBOMEX S.A de C.V” by a phenolic urethane no-bake sand mold casting method. During functioning, camshafts are subject to bending and torsional stresses, and the lobe surfaces are highly loaded. Thus, high toughness and wear resistance are essential for this component. In this work, two austempering ductile iron heat treatments were evaluated to increase the mechanical properties of tensile strength, hardness, and toughness of the ductile iron camshaft low alloyed with vanadium. The austempering process was held at 265 and 305 °C and austempering times of 30, 60, 90, and 120 min. The volume fraction of high-carbon austenite was determined for the heat treatment conditions by XRD measurements. The ausferritic matrix was determined in 90 min for both austempering temperatures, having a good agreement with the microstructural and hardness evolution as the austempering time increased. The mechanical properties of tensile strength, hardness, and toughness were evaluated from samples obtained from the camshaft and the standard Keel block. The highest mechanical properties were obtained for the austempering heat treatment of 265 °C for 90 min for the ADI containing 0.3 wt % V. The tensile and yield strength were 1200 and 1051 MPa, respectively, while the hardness and the energy impact values were of 47 HRC and 26 J; these values are in the range expected for an ADI grade 3.

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