Toward a better understanding of chemical and microstructure heterogeneities inherited from solidification and solid state phase transformations in the Ti-48Al-2Cr-2Nb alloy

2004 ◽  
Vol 92 (1-2) ◽  
pp. 39-50 ◽  
Author(s):  
M. Charpentier ◽  
D. Daloz ◽  
A. Hazotte ◽  
E. Aeby-Gautier
Keyword(s):  
Solid State ◽  
Phase Transformations

The use of high-resolution FESEM to study solid-state phase transformations and reactions

1994 ◽  
Vol 52 ◽  
pp. 1028-1029
Author(s):  
P. G. Kotula ◽  
D. D. Erickson ◽  
C. B. Carter
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Phase Transformations ◽  
High Efficiency ◽  
Sol Gel ◽  
Quantitative Information ◽  
Solid State Reactions ◽  
Critical Dimensions ◽  
Backscattered Electrons ◽  
Backscattered Electron

High-resolution field-emission-gun scanning electron microscopy (FESEM) has recently emerged as an extremely powerful method for characterizing the micro- or nanostructure of materials. The development of high efficiency backscattered-electron detectors has increased the resolution attainable with backscattered-electrons to almost that attainable with secondary-electrons. This increased resolution allows backscattered-electron imaging to be utilized to study materials once possible only by TEM. In addition to providing quantitative information, such as critical dimensions, SEM is more statistically representative. That is, the amount of material that can be sampled with SEM for a given measurement is many orders of magnitude greater than that with TEM.In the present work, a Hitachi S-900 FESEM (operating at 5kV) equipped with a high-resolution backscattered electron detector, has been used to study the α-Fe2O3 enhanced or seeded solid-state phase transformations of sol-gel alumina and solid-state reactions in the NiO/α-Al2O3 system. In both cases, a thin-film cross-section approach has been developed to facilitate the investigation. Specifically, the FESEM allows transformed- or reaction-layer thicknesses along interfaces that are millimeters in length to be measured with a resolution of better than 10nm.

scholarly journals A review on the modeling and simulations of solid-state diffusional phase transformations in metals and alloys

2018 ◽  
Vol 5 ◽  
pp. 10 ◽  
Author(s):  
Xueyan Liu ◽  
Hongwei Li ◽  
Mei Zhan
Keyword(s):  
Solid State ◽  
Phase Transformations ◽  
Numerical Technique ◽  
Metals And Alloys ◽  
Analytical Models ◽  
Theoretical Research ◽  
Current Status ◽  
Advantages And Disadvantages ◽  
Simulation Techniques ◽  
Molecular Dynamics Methods

Solid-state diffusional phase transformations are vital approaches for controlling of the material microstructure and thus tailoring the properties of metals and alloys. To exploit this mean to a full extent, much effort is paid on the reliable and efficient modeling and simulation of the phase transformations. This work gives an overview of the developments in theoretical research of solid-state diffusional phase transformations and the current status of various numerical simulation techniques such as empirical and analytical models, phase field, cellular automaton methods, Monte Carlo models and molecular dynamics methods. In terms of underlying assumptions, physical relevance, implementation and computational efficiency for the simulation of phase transformations, the advantages and disadvantages of each numerical technique are discussed. Finally, trends or future directions of the quantitative simulation of solid-state diffusional phase transformation are provided.

scholarly journals Modeling Solid-State Phase Transformations of 13Cr-4Ni Steels in Welding Heat-Affected Zone

2019 ◽  
Vol 51 (3) ◽  
pp. 1208-1220
Author(s):  
J. B. Lévesque ◽  
J. Lanteigne ◽  
H. Champliaud ◽  
D. Paquet
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Solid State ◽  
Martensitic Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Heat Affected Zone ◽  
Martensitic Stainless Steel ◽  
Fatigue Crack Initiation ◽  
Hydraulic Turbine

AbstractFatigue damage is commonly encountered by operators of Francis type hydraulic turbine runners made of 13Cr-4Ni soft martensitic stainless steel. These large and complex welded casting assemblies are subjected to fatigue crack initiation and growth in the vicinity of their welded regions. It is well known that fatigue behavior is influenced by residual stresses and the microstructure. By including solid-state phase transformation models in welding simulations, phase distribution can be evaluated along with their respective volumetric change and their effect on residual stresses. Thus, it enables the assessment of welding process on fatigue crack behavior by numerical methods. This paper focuses on modeling solid-state phase transformations of 13Cr-4Ni soft martensitic stainless steel, used for manufacturing hydraulic turbine runners, occurring upon welding. It proposes to determine the material parameters of the models for both the austenitic and the martensitic transformation by nonisothermal dilatometry tests. The experiments are conducted in a quenching dilatometer with applied thermal conditions as experienced in the heat-affected zone of homogeneous welds. The activation energy and the kinetic parameters of the austenitic transformation from fully martensitic state are measured from the experimental results. The martensitic transformation modeling from a fully austenitic domain is also presented.

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