Phase Transformation and Recovery Stress of Ni47Ti44Nb9 Alloy During Constrained Heating and Cooling

2019 ◽  
Vol 51 (1) ◽  
pp. 390-399 ◽  
Author(s):  
Q. C. Fan ◽  
M. Y. Sun ◽  
Y. Y. Wang ◽  
K. H. Sun ◽  
X. D. Cao ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Recovery Stress ◽  
Heating And Cooling

scholarly journals Thermodynamical Modelling of Recovery Stress Associated with R-Phase Transformation in TiNi Shape Memory Alloys

1994 ◽  
Vol 35 (5) ◽  
pp. 325-331 ◽  
Author(s):  
Sylvain Leclercq ◽  
Christian Lexcellent ◽  
Hisaaki Tobushi ◽  
Ping-Hua Lin
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Recovery Stress

In situ Transmission Electron Microscopy and Nanoindentation Studies of Phase Transformation and Pseudoelasticity of Shape-memory Titanium-nickel Films

2005 ◽  
Vol 20 (7) ◽  
pp. 1808-1813 ◽  
Author(s):  
X.-G. Ma ◽  
K. Komvopoulos
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Transformation ◽  
Shape Memory ◽  
Heating And Cooling ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Titanium Nickel ◽  
In Situ Heating

Transmission electron microscopy (TEM) and nanoindentation, both with in situ heating capability, and electrical resistivity measurements were used to investigate phase transformation phenomena and thermomechanical behavior of shape-memory titanium-nickel (TiNi) films. The mechanisms responsible for phase transformation in the nearly equiatomic TiNi films were revealed by heating and cooling the samples inside the TEM vacuum chamber. Insight into the deformation behavior of the TiNi films was obtained from the nanoindentation response at different temperatures. A transition from elastic-plastic to pseudoelastic deformation of the martensitic TiNi films was encountered during indentation and heating. In contrast to the traditional belief, the martensitic TiNi films exhibited a pseudoelastic behavior during nanoindentation within a specific temperature range. This unexpected behavior is interpreted in terms of the evolution of martensitic variants and changes in the mobility of the twinned structures in the martensitic TiNi films, observed with the TEM during in situ heating.

New Method of Quench Surface Turning

2017 ◽  
Vol 265 ◽  
pp. 696-701 ◽  
Author(s):  
N.N. Zubkov ◽  
S.G. Vasil'ev ◽  
V.V. Poptsov
Keyword(s):  
Phase Transformation ◽  
Steel Surface ◽  
Hardened Steel ◽  
Surface Structures ◽  
Heating And Cooling ◽  
Surface Quenching ◽  
Steel Surfaces ◽  
Deformational Cutting ◽  
Chip Separation ◽  
Hardened Surface

The heating, generated in the process of deformational cutting without chip separation used for phase transformation in steel during lathe machining. Chips are not separated from the workpiece and remain on the surface thus forming a special reinforced structure. The result of processing is a steel surface quenching up to 1 mm deep. The proposed method also makes it possible to obtain hardened surface structures with alternating inclined layers of different hardness. The article presents calculations of heating and cooling rates, types of hardened structures, hardness investigation of hardened steel surfaces.

scholarly journals Thermal Arrest Memory Effect in Ni-Mn-Ga Alloys

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
A. Rudajevova
Keyword(s):  
Phase Transformation ◽  
Memory Effect ◽  
Thermal Cycle ◽  
Cylindrical Sample ◽  
Sample Length ◽  
Thermal Arrest ◽  
Focusing Effect ◽  
Heating And Cooling ◽  
Original Length ◽  
Length Analysis

Dilatation characteristics were measured to investigate the thermal arrest memory effect inNi53.6Mn27.1Ga19.3andNi54.2Mn29.4Ga16.4alloys. Interruption of the martensite-austenite phase transformation is connected with the reduction of the sample length after thermal cycle. If a total phase transformation took place in the complete thermal cycle following the interruption, then the sample length would return to its original length. Analysis of these results has shown that the thermal arrest memory effect is a consequence of a stress-focusing effect and shape memory effect. The stress-focusing effect occurs when the phase transformation propagates radially in a cylindrical sample from the surface, inward to the center. Evolution and release of the thermoelastic deformations in both alloys during heating and cooling are analyzed.

NUMERICAL MODELING OF PHASE TRANSFORMATION DURING GRINDING PROCESS

2017 ◽  
Vol 79 (5) ◽  
Author(s):  
Syed Mushtaq Ahmed Shah ◽  
M. A. Khattak ◽  
Muhammad Asad ◽  
Javed Iqbal ◽  
Saeed Badshah ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Thermal Stresses ◽  
Heating Temperature ◽  
Temperature History ◽  
Grinding Process ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Heating And Cooling

The rapid heating and cooling in a grinding process may cause phase transformations. This will introduce thermal strains and plastic strains simultaneously in a workpiece with substantial residual stresses. The properties of the workpiece material will change when phase transformation occurs. The extent of such change depends on the temperature history experienced and the instantaneous thermal stresses developed. To carry out a reliable residual stress analysis, a comprehensive modelling technique and a sophisticated computational procedure that can accommodate the property change with the metallurgical change of material need to be developed. The objective of this work is to propose a simplified model to predict phase evolution during given temperature history for heating and cooling as encountered during grinding process. The numerical implementation of the proposed model is carried out through the developed FORTRAN subroutine called PHASE using the FEM commercial software Abaqus®/standard. Micro-structural constituents are defined as state variables. They are computed and updated inside the subroutine PHASE. The heating temperature is assumed to be uniform while the cooling characteristics in relation to phase transformations are obtained from the continuous cooling transformation (CCT) diagram of the given material (here AISI 52100 steel). Four metallurgical phases are assumed for the simulations: austenite, pearlite, bainite, and martensite. It was shown that at low cooling rates high percentage of pearlite phase is obtained when the material is heated and cooled to ambient temperature. Bainite is formed usually at medium cooling rates. Similarly at high cooling rates maximum content of martensite may be observed. It is also shown that the continuous cooling transformation kinetics may be described by plotting the transformation temperature, directly against the cooling rate as an alternative to the continuous cooling transformation diagram. The simulated results are also compared with experimental results of Wever [20] and Hunkle [21] and are found to be in a very good agreement. The model may be used for further thermo-mechanical analysis coupled with phase transformation during grinding process.

Study of Thermo-Physical Properties of Selected Nickel-Based Superalloys With Use of DTA Method

2012 ◽  
Author(s):  
Jana Dobrovska ◽  
Simona Zla ◽  
Frantisek Kavicka ◽  
Bedrich Smetana ◽  
Vlastimil Vodarek
Keyword(s):  
Phase Transformation ◽  
Physical Properties ◽  
Phase Transformations ◽  
Solidus Temperature ◽  
Experimental System ◽  
Reaction Scheme ◽  
Transformation Temperatures ◽  
Heating And Cooling ◽  
Temperature Heating ◽  
Thermo Physical Properties

The presented paper deals with study of thermo-physical properties of cast complex alloyed nickel based superalloys IN713LC, IN738LC and IN792-5A. In this work the technique of Differential Thermal Analysis was selected for acquisition and comparison of the phase transformation temperatures. The samples taken from superalloys in as received state were analysed at heating and cooling rates of 1, 5, 10, and 20 K/min using the experimental system Setaram SETSYS 18TM. Moreover, the transformation temperatures for zero heating/cooling rate were calculated. Based on a comparison of these temperatures it is possible to make the following conclusions: (i) The alloy IN792-5A has the highest temperature of solubility of the strengthening phase γ′ (1235°C); (ii) the highest liquidus temperature (heating) obtained by extrapolation was found in the alloy IN713LC (1349°C), the lowest solidus temperature (heating) was found for the alloy IN738LC (1212°C); (iii) At cooling an undercooling occurred in all alloys. In general it may be stated that the biggest under-cooling (TS, 47°C) was recorded in the alloy IN792 5A; (iv) The width of the interval of the heat treatment window was the biggest in alloy IN713LC (44°C); (v) The alloy IN738LC is characterised by the widest interval of melting (124°C) and solidification (134°C), while the alloy IN792 5A has the narrowest interval of melting (82°C) and at the same time almost the same interval of solidification as the alloy IN738LC (129°C); (vi) The obtained phase transformation temperatures were compared with the values of phase transformations temperatures calculated on the basis of established relationships. In order to obtain more precise description of the behaviour of Ni-based superalloys, during controlled heating/cooling of the initial material (as received state) during DTA analyses, all the samples of superalloys were subjected to a phase analysis using scanning electron microscopy. The course of phase transformations, in all the studied superalloys (IN713LC, IN738LC, IN792 5A) is likely to run according to the following reaction scheme (L = melt): L ↔ γ, L ↔ γ + MC, L ↔ γ/γ′, L ↔ γ + minority phases (such as M3B2, phase η), γ ↔ γ′.

scholarly journals Microstructural Evolution and Element Partitioning in the Phase Transformation of Ti-17 Alloy under Continuous Heating and Cooling Conditions

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1054
Author(s):  
Xudong An ◽  
Xin Cai ◽  
Mingpan Wan ◽  
Min Lei ◽  
Chaowen Huang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Continuous Heating ◽  
Alloying Element ◽  
Heating And Cooling ◽  
Β Phase ◽  
Cooling Conditions ◽  
Α Phase ◽  
Element Partitioning ◽  
The Matrix

The microstructural evolution and alloying element partitioning in the α + β ↔ β phase transformation of Ti-17 alloy were explored under continuous heating and cooling conditions using the dilatometric method. Scanning electron microscopy and transmission electron microscopy were used to evaluate microstructural characteristics and trace alloying element partitioning behaviors occurring at different temperatures during heating and cooling. Results showed that the finer needle-like α phase first dissolved into the β phase in the matrix with increasing temperature, while the grain boundary α phase first coarsened and then transformed gradually into β phase during continuous heating. The dissolution of α phase of the alloy with the alloying element partitioning during continuous heating was observed. On the contrary, αGB formed at the prior β grain of the alloy during continuous cooling, which might be the nuclei of α colony, thus resulting in the formation of α colony in the matrix. As the temperature decreased, the elements’ concentrations in the α and β phases became increasingly varied due to element partition. Moreover, Al and Cr, which had higher diffusion coefficients than Mo, easily reached the concentration equilibrium of alloying elements in the α and β phases, respectively. The shrinkage of dilatometric curves during heating in the Ti-17 alloy are mainly attributed to the change of α-HCP (hexagonal close-packed) lattice to β-BCC (body-centered cubic) lattice; while the element partitioning during the β → α + β transformation plays an important role in the shrinkage of the dilatometric curves of the Ti-17 alloy during cooling.

scholarly journals Phase Transformation of High Velocity Air Fuel (HVAF)-Sprayed Al-Cu-Fe-Si Quasicrystalline Coating

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 834
Author(s):  
Mingwei Cai ◽  
Jun Shen
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Amorphous Phase ◽  
High Velocity ◽  
Quasicrystalline Phase ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling ◽  
Transmission Electron ◽  
The Difference

Al-Cu-Fe-Si quasicrystalline coatings were prepared by high velocity air fuel spraying to study their phase transformation during the process. The feedstock powder and coating were phase characterized by scanning electron microscopy, X-ray diffractometry, differential scanning calorimetry, and transmission electron microscopy. Results show that Al3Cu2 phase, a small amount of λ-Al13Fe4 phase, quasicrystalline phase (QC), amorphous phase, and β-Al (Cu, Fe, Si) phase were present in the sprayed Al50Cu20Fe15Si15 powder. For a typical flattened powder particle, the splat periphery was surrounded by a 1 µm thick amorphous phase. The inside area of the splat was composed of the QC covered by the Al3Cu2 and Si-rich β-Al (Cu, Fe, Si) phases. Another kind of Cu- rich β-Al (Cu, Fe, Si) phase can be found close to the amorphous area with a similar composition to the original β-Al (Cu, Fe, Si) phase in the powder. Different phases were observed when the periphery and inside area of the splat were compared. This result was caused by the difference in the heating and cooling rates.

Microstructure and Phase Transformation Behavior of Ni-Mn-Fe High-Temperature Shape Memory Alloys

2015 ◽  
Vol 833 ◽  
pp. 63-66
Author(s):  
Cui Ping Wang ◽  
Yu Ding Liu ◽  
Shui Yuan Yang ◽  
Xing Jun Liu
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Transformation Behavior ◽  
Phase Transformation Behavior ◽  
Heating And Cooling ◽  
High Transformation ◽  
Irreversible Phase Transformation ◽  
Very High

The microstructure and phase transformation behavior of Ni-Mn-Fe high-temperature shape memory alloys including Ni40+xFe10Mn50-x (x = 0, 10) were investigated. The results show that both two alloys exhibit single fcc γ phase annealed at 900°C for 1 day. When these quenched alloys are again annealed at 500°C for 20 days, they almost exhibit main tetragonal θ martensite. The microstructural evolutions are consistent with the results of phase transformation measurements. It is clearly found that there is an irreversible phase transformation around 480°C ~ 570°C, which is associated with the formation of tetragonal θ martensite from γ phase. Afterwards, the reversible martensitic transformation occurs during heating and cooling with very high transformation temperature.

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