scholarly journals Interpretations of Cooling Dilatograms in the Range of the Bainitic and Martensitic Transformations/ Intwerpretacja Dylatogramów Chłodzenia W Zakresie Przemiany Bainitycznej I Martenzytycznej

2014 ◽  
Vol 59 (4) ◽  
pp. 1679-1683 ◽  
Author(s):  
J. Pacyna
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Martensitic Transformations ◽  
Lower Bainite ◽  
Correct Interpretation ◽  
Dilatometric Curve ◽  
Treatment Technologies ◽  
The Stability ◽  
Kinetics Of ◽  
Undercooled Austenite

Abstract The method of interpretation of cooling dilatograms of undercooled austenite during its transformation into upper and lower bainite (UB and LB) and into martensite (M), applied in the Laboratory of Phase Transformations of AGH University of Science and Technology in Krakow, is presented in the hereby paper. The relation of the mechanism of the mentioned above transformations to places on the dilatometric curve where transformations start and where they are continued was indicated. An appeal for the unified, correct interpretation of dilatograms of phase transformations, in all laboratories of the world, was formulated. This will allow the formation of equally accurate diagrams of the kinetics of phase transformation of undercooled austenite at its continuous cooling (CCT). In consequence, this could provide a development of more advanced heat treatment technologies. Such approach will also allow for the correct assessment of the influence of the alloying elements on the stability of austenite and phase transformation temperatures at its cooling.

scholarly journals The Phase Transformations in Hypoeutectoid Steels Mn-Cr-Ni

2015 ◽  
Vol 60 (1) ◽  
pp. 497-502 ◽  
Author(s):  
E. RoŻniata ◽  
R. Dziurka
Keyword(s):  
Chemical Composition ◽  
Phase Transformations ◽  
Critical Points ◽  
Light Microscope ◽  
Cooling Curves ◽  
Critical Temperatures ◽  
Martensitic Microstructure ◽  
Cct Diagrams ◽  
Kinetics Of ◽  
Undercooled Austenite

Abstract The results of a microstructure and hardness investigations of the hypoeutectoid steels Mn-Cr-Ni, imitating by its chemical composition toughening steels, are presented in the paper. The analysis of the kinetics of phase transformations of undercooled austenite of steels containing different amounts of alloying elements in their chemical composition, constitutes the aim of investigations. Metallographic examinations were carried out on a Axiovert 200 MAT light microscope. Sections were etched with a 3% HNO3 solution in C2H5OH. Dilatometric tests were performed using L78 R.I.T.A dilatometer. Using dilatometer the changes of elongation (Δl) of the samples with dimensions Ø 3×10 mm as a function of temperature (T) were registered. Obtained heating curves were used to precisely determine the critical temperatures (critical points) for the tested steels, while the differentiation of obtained cooling curves allowed to precisely define the temperatures of the beginning and the end of particular transition to draw CCT diagrams. Four CCT diagrams worked out for the tested hypoeutectoid steels (for quenching of steel) are - in the majority of steels - separated by the undercooled austenitic range and are of the letter „C” shape. However, for steels with Mn and Ni the separation of diffusive transformations from the bainitic transformation by the stable austenitic range is not observed. Hardenability of four investigated hypoeutectoid steels is similar, but still not high. To obtain martensite in the microstructure of these steels, it is necessary to apply the cooling rate higher than 25°C/s. The exception constitutes the Mn - Ni steel, in which only cooling with the rate higher than 50°C/s allows to achieve the martensitic microstructure and to avoid diffusive transformations (pearlitic and ferritic).

The use of lattice-parameter changes to trace the kinetics of phase transformations powder-diffraction analysis of disorder-order transformations in Ni1+δSn

2007 ◽  
Vol 222 (3-4) ◽  
Author(s):  
Andreas Leineweber ◽  
Eric J. Mittemeijer
Keyword(s):  
Phase Transformation ◽  
Diffraction Analysis ◽  
Phase Transformations ◽  
Powder Diffraction ◽  
Lattice Parameter ◽  
X Ray ◽  
Kinetics Of

The measurement of lattice-parameter changes by X-ray powder diffraction as a function of the progress of a phase transformation (

A Mixed-Mode Model Considering Soft Impingement Effects for Solid-State Partitioning Phase Transformations

2011 ◽  
Vol 172-174 ◽  
pp. 561-566 ◽  
Author(s):  
Hao Chen ◽  
Sybrand van der Zwaag
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Numerical Solution ◽  
Phase Transformations ◽  
Concentration Gradient ◽  
Mixed Mode ◽  
Original Model ◽  
Polynomial Method ◽  
Soft Impingement ◽  
Kinetics Of

The original mixed-mode model is reformulated by considering the soft impingement effect and applying a general polynomial method of dealing with the concentration gradient in front of the interface. Comparison with the numerical solution shows that the reformulated mixed-mode model is more precise than the original model. The effect of soft impingement on the kinetics of partitioning phase transformation depends on both the growth mode and the degree of super-saturation.

Prediction of the kinetics of the phase transformations and the associated microstructure during continuous coolingin the Ti17

2004 ◽  
Vol 120 ◽  
pp. 93-101
Author(s):  
J. Da Costa Teixeira ◽  
L. Héricher ◽  
B. Appolaire ◽  
E. Aeby-Gautier ◽  
G. Cailletaud ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Phase Field ◽  
Experimental Results ◽  
Thermal Treatments ◽  
Thermal Gradients ◽  
Resistivity Measurements ◽  
Isothermal Conditions ◽  
Kinetics Of

The aim of this paper is to present recent experimental results and related simulation about the β → αGB + αWGB and → αWI transformations which occur in the Ti17 alloy during the thermal treatments following the heating in the β phase field. These phase transformations were experimentally studied under isothermal conditions in samples with negligible thermal gradients. The IT diagram was obtained, on the basis of electrical resistivity measurements and microstructural SEM observations. The kinetics of the phase transformation was further numerically simulated for continuous cooling on the basis of a formerly developed model giving the amount of each morphology (αWGB, αWI). Experimental and calculated results are compared.

Investigation of the effects of phase transformations in micro and nano aluminum powders on kinetics of oxidation using thermogravimetric analysis

2017 ◽  
Vol 19 (29) ◽  
pp. 18996-19009 ◽  
Author(s):  
Florin Saceleanu ◽  
Sanam Atashin ◽  
John Z. Wen
Keyword(s):  
Phase Transformation ◽  
Thermogravimetric Analysis ◽  
Phase Transformations ◽  
Kinetics Of Oxidation ◽  
Aluminum Powders ◽  
Kinetics Of

Phase transformation within the alumina shell controls kinetics of oxidation and corresponding mass diffusivities.

scholarly journals Improper Interpretation of Dilatometric Data for Cooling Transformation in Steels

2014 ◽  
Vol 59 (3) ◽  
pp. 1159-1161 ◽  
Author(s):  
B. Pawłowski ◽  
P. Bała ◽  
R. Dziurka
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Real Time ◽  
Dimensional Change ◽  
Real Time Monitoring ◽  
Dilatometric Curve ◽  
Dimensional Changes ◽  
Cct Diagrams ◽  
Wrong Interpretation ◽  
Dilatometric Data

Abstract Dilatometry is the most commonly method of producing CCT diagrams and analyzing phase transformations during cooling (as well as transformations during heating) and it permits the real-time monitoring of the extent of reaction in terms of dimensional changes due to phase transformation. All modern dilatometers are fitted with computerised systems which collect dimensional change signals versus temperature to plot a dilatometric curve and also to calculate and plot the derivative of the relative dimensional change with respect to temperature. Unfortunately, elaborated by dilatometers manufacturers software, in many cases could lead to wrong interpretation of phase transformations during cooling.

scholarly journals EVOLUTION OF A DISLOCATION STRUCTURE DURING THE GROWTH SILICON SINGLE CRYSTALS OF n- AND p-TYPE

2020 ◽  
pp. 44-50
Author(s):  
N.A. Azarenkov ◽  
V.E. Semenenko ◽  
N.G. Stervoyedov
Keyword(s):  
Phase Transformation ◽  
Single Crystals ◽  
Dislocation Structure ◽  
Semiconductor Devices ◽  
Screw Dislocations ◽  
Linear Defects ◽  
The Stability ◽  
P Type ◽  
Kinetics Of ◽  
Concentration Of Impurities

The kinetics of the formation of perfect n- and p-type silicon single crystals is considered. The peculiarity of the formation of point and linear defects in the process of a controlled phase transformation of a liquid-solid is established. The effect of supersaturation by vacancies of the direction of predominant growth and concentration of impurities on the formation and removal of edge and screw dislocations is determined. The effect of linear defects on the scattering and recombination of mobile current carriers is revealed. The possibilities of increasing the stability and efficiency of silicon semiconductor devices are discussed.

Microstructures and Phase Transformations of Ti-50.9at%Ni Alloy Processed by Equal Channel Angular Extrusion at Medium Temperature

2007 ◽  
Vol 561-565 ◽  
pp. 877-880 ◽  
Author(s):  
Chao Ying Xie ◽  
Zhi Guo Fan
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Equal Channel Angular Extrusion ◽  
Martensitic Transformations ◽  
Optical Microscope ◽  
Medium Temperature ◽  
Thermal Peak ◽  
Ni Alloy ◽  
Coarse Grains ◽  
Angular Extrusion

Submicron-grained Ti-50.9at%Ni alloy was prepared by Equal Channel Angular Extrusion (ECAE) at medium temperature(500°C). Microstructure evolution and phase transformations of Ti-50.9at%Ni alloy after ECAE processes at medium temperature have been investigated by optical microscope, TEM and DSC tests. It is found that the initial coarse grains of Ti-50.9at%Ni alloy were refined into submicron grains, smaller than 0.5 um in size, after eight passes ECAE at 500°C. Martensitic transformation temperatures decreased remarkably after one pass ECAE and more gently with increasing the pass number of ECAE. R phase transformation was stimulated after ECAE processes and underwent within a larger temperature range with an ambiguous thermal peak. The reverse R phase and reverse martensitic transformations, during heating, were separated eventually after eight passes ECAE.

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