scholarly journals Deformation Behavior of a β-Solidifying TiAl Alloy within β Phase Field and Its Effect on the β→α Transformation

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 605 ◽  
Author(s):  
Yi Chen ◽  
Liang Cheng ◽  
Guang Yang ◽  
Yalin Lu ◽  
Fengbo Han
Keyword(s):  
Phase Field ◽  
Deformation Behavior ◽  
Single Phase ◽  
Tial Alloy ◽  
Volume Fraction ◽  
Dislocation Creep ◽  
Strain Rates ◽  
Texture Intensity ◽  
Β Phase ◽  
Single Phase Field

In this study, the deformation behavior of a Ti-40Al-10V (at.%) alloy within β single phase field was examined by means of isothermal compression at 1300 °C under strain rates of 2 s−1, 0.2 s−1, and 0.02 s−1, as well as its effect on the subsequent β→α transformation. The results showed that the alloy behaved steady-state flow with dislocation creep as the predominant rate-controlling process. Dynamic recrystallization (DRX) evidently occurred during deformation, and its volume fraction was dramatically increased so that at the lowest strain rate (0.02 s−1), a full-DRX β structure was obtained. The preferentially dynamic migration of grain boundaries with <100> orientation was demonstrated to be the major DRX mechanism. The texture was characterized by a <100> + <111> double-fiber at 2 s−1, but gradually transformed into a simple rotated cube orientationunder 0.02 s−1, accompanied by a decreasing texture intensity. During the subsequent β→α transformation, two types of α morphology wereproduced with evident variant selection, namely, the Widmannstatten colony and martensitic laths. Texture simulation revealed that the α texture was solely determined by parent β texture, despite of the variant selections.

Constitutive Analysis of the High-Temperature Deformation Behavior of Single Phase α-Ti and α+β Ti-6Al-4V Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 3607-3612 ◽  
Author(s):  
Jeoung Han Kim ◽  
Jong Taek Yeom ◽  
Nho Kwang Park ◽  
Chong Soo Lee
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Deformation Behavior ◽  
Single Phase ◽  
Volume Fraction ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Β Phase ◽  
Α Phase ◽  
Self Consistent

The high-temperature deformation behavior of the single-phase α (Ti-7.0Al-1.5V) and α + β (Ti-6Al-4V) alloy were determined and compared within the framework of self-consistent scheme at various temperature ranges. For this purpose, isothermal hot compression tests were conducted at temperatures between 650°C ~ 950°C to determine the effect of α/β phase volume fraction on average flow stress under hot-working condition. The flow behavior of α phase was estimated from the compression test results of single-phase α alloy whose chemical composition is close to that of α phase of Ti-6Al-4V alloy. On the other hand, the flow stress of β phase in Ti-6Al-4V was predicted by using self-consistent method. The flow stress of α phase was higher than that of β phase above 750°C, while the β phase revealed higher flow stress than α phase at 650°C. Also, at temperature above 750°C, the predicted strain rate of β phase was higher than that of α phase. It was found that the relative strength between α and β phase significantly varied with temperature.

Effect of Strain Rate on the Microstructure and β-Texture Evolutions in β-Processed Forging of a Near-β Titanium Alloy

2021 ◽  
Vol 1016 ◽  
pp. 882-887
Author(s):  
Ling Jian Meng ◽  
Tomonori Kitashima
Keyword(s):  
Strain Rate ◽  
Compression Ratio ◽  
Single Phase ◽  
Texture Evolution ◽  
Hot Forging ◽  
Phase Region ◽  
Strain Rates ◽  
Texture Intensity ◽  
Β Phase ◽  
Α Phase

The effect of strain rate on the β texture evolution during two-step hot forging of Ti-6246 alloy was investigated. The two-step forging consisted of 15% or 50% prior-β forging at 980°C and subsequent 60% or 25% forging at 870°C in the (α + β) dual-phase region. The total compression ratio was 75%, and the investigated strain rates were 0.01 and 1.0 s−1. The β forging texture showed typical {001} and {111} body-centered cubic textures. With increasing compression ratio in the (α + β) region and at a strain rate of 0.01 s−1, the amount of precipitated α phase increased. Dynamic recrystallization was rarely observed after forging in the (α + β) region at a strain rate of 0.01 s−1. Large amounts of α precipitates lowered the {001} β texture intensity through slip transmission between the α and β phases under the Burgers orientation relationship. However, in specimens forged at a strain rate of 1.0 s−1, as the compression ratio in the β single-phase region increased, the growth of dynamic-recrystallized β grains was promoted at the prior-β grain boundaries, where α-phase precipitation was not substantial. These effects resulted in a higher {001} texture intensity of the β phase in specimens forged at 1.0 s−1 compared with that of the β phase in specimens forged at 0.01 s−1.

A TEM study of the influence of microstructure on the superplastic behavior of a U-5.8 wt.% Nb alloy

1986 ◽  
Vol 44 ◽  
pp. 568-569
Author(s):  
G. Mackiewicz Ludtka
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Phase Field ◽  
Single Phase ◽  
Superplastic Behavior ◽  
Two Phase ◽  
Single Phase Field

Historically, metals exhibit superplasticity only while forming in a two-phase field because a two-phase microstructure helps ensure a fine, stable grain size. In the U-5.8 Nb alloy, superplastici ty exists for up to 2 h in the single phase field (γ1) at 670°C. This is above the equilibrium monotectoid temperature of 647°C. Utilizing dilatometry, the superplastic (SP) U-5.8 Nb alloy requires superheating to 658°C to initiate the α+γ2 → γ1 transformation at a heating rate of 1.5°C/s. Hence, the U-5.8 Nb alloy exhibits an anomolous superplastic behavior.

scholarly journals Modular Rotor Single Phase Field Excited Flux Switching Machine with Non-Overlapped Windings

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1576 ◽  
Author(s):  
Lutf Ur Rahman ◽  
Faisal Khan ◽  
Muhammad Afzal Khan ◽  
Naseer Ahmad ◽  
Hamid Ali Khan ◽  
...  
Keyword(s):  
Phase Field ◽  
Single Phase ◽  
Dead Zone ◽  
Optimization Technique ◽  
Rotor Design ◽  
Iron Losses ◽  
Excitation Coil ◽  
Electromagnetic Performance ◽  
Copper Losses ◽  
Single Phase Field

This paper aims to propose and compare three new structures of single-phase field excited flux switching machine for pedestal fan application. Conventional six-slot/three-pole salient rotor design has better performance in terms of torque, whilst also having a higher back-EMF and unbalanced electromagnetic forces. Due to the alignment position of the rotor pole with stator teeth, the salient rotor design could not generate torque (called dead zone torque). A new structure having sub-part rotor design has the capability to eliminate dead zone torque. Both the conventional eight-slot/four-pole sub-part rotor design and six-slot/three-pole salient rotor design have an overlapped winding arrangement between armature coil and field excitation coil that depicts high copper losses as well as results in increased size of motor. Additionally, a field excited flux switching machine with a salient structure of the rotor has high flux strength in the stator-core that has considerable impact on high iron losses. Therefore, a novel topology in terms of modular rotor of single-phase field excited flux switching machine with eight-slot/six-pole configuration is proposed, which enable non-overlap arrangement between armature coil and FEC winding that facilitates reduction in the copper losses. The proposed modular rotor design acquires reduced iron losses as well as reduced active rotor mass comparatively to conventional rotor design. It is very persuasive to analyze the range of speed for these rotors to avoid cracks and deformation, the maximum tensile strength (can be measured with principal stress in research) of the rotor analysis is conducted using JMAG. A deterministic optimization technique is implemented to enhance the electromagnetic performance of eight-slot/six-pole modular rotor design. The electromagnetic performance of the conventional sub-part rotor design, doubly salient rotor design, and proposed novel-modular rotor design is analyzed by 3D-finite element analysis (3D-FEA), including flux linkage, flux distribution, flux strength, back-EMF, cogging torque, torque characteristics, iron losses, and efficiency.

Hot deformation behavior of ZrTiAlV alloy with a coarse grain structure in the β phase field

2013 ◽  
Vol 577 ◽  
pp. 218-224 ◽  
Author(s):  
Y.B. Tan ◽  
L.H. Yang ◽  
C. Tian ◽  
R.P. Liu ◽  
X.Y. Zhang ◽  
...  
Keyword(s):  
Phase Field ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Grain Structure ◽  
Coarse Grain ◽  
Hot Deformation Behavior ◽  
Β Phase

Phase Stability and Mechanical Properties of Ti-Cr-Sn-Zr Alloys Containing a Large Amount of Zr

2016 ◽  
Vol 879 ◽  
pp. 1344-1349 ◽  
Author(s):  
Yonosuke Murayama ◽  
Erdnechuluun Enkhjavkhlan ◽  
Akihiko Chiba
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Deformation Behavior ◽  
Single Phase ◽  
Young's Modulus ◽  
Martensitic Structure ◽  
Β Phase ◽  
Microstructural Transition ◽  
Zr Alloy ◽  
Zr Alloys

The Young’s modulus of Ti-Cr-Sn-Zr alloy varies with the composition of Cr, Sn and Zr, in which the elements act as β stabilizers. Some Ti-Cr-Sn-Zr alloys show very low Young’s modulus under 50GPa. The amount of Zr in alloys with very low Young's modulus increases with the decrease of Cr. We investigated the Young’s modulus and deformation behavior of Ti-xCr-Sn-Zr (x=0~1mass%) alloys containing a large amount of Zr. The quenched microstructure of Ti-Cr-Sn-Zr alloys changes from martensitic structure to β single-phase structure if the amounts of β stabilized elements are increased. The Ti-Cr-Sn-Zr alloys with compositions close to the transitional composition of microstructure from martensite to β phase show minimum Young’s modulus. The clear microstructural transition disappears and the minimum Young’s modulus increases if the amount of Cr becomes too small. In Ti-Cr-Sn-Zr alloys containing a large amount of Zr, Young’s modulus depends on β phase that is intermingled with martensite.

Superconductivity in the (Nd,Ce,Ca)2Cuo4-Z System

1989 ◽  
Vol 169 ◽  
Author(s):  
Takeshi Sakurai ◽  
Toru Yamashita ◽  
Sumio Ikegawa ◽  
H. Yamauchi
Keyword(s):  
Phase Field ◽  
Carrier Density ◽  
Single Phase ◽  
Superconducting Transition ◽  
X Ray ◽  
Analysis Techniques ◽  
Density Relationship ◽  
Micro Analysis ◽  
T Phase ◽  
Single Phase Field

AbstractWe have controlled the carrier (electron) density in Nd2CuO2 of the T’ structure by introducing both Ce and Ca into the Nd‐sites, and studied the superconducting transition temperature versus carrier density relationship. The phase relations in the (Nd1‐x‐yCexCay)2CuO4‐z system were studied by means of powder X‐ray dirfractron and electron‐probe micro‐analysis techniques. For the phase diagram of the (Nd1‐x‐yCexCay)2CuO4‐z system, the single phase field of the T’ phase was established. Samples of the (Nd0.9‐yCe0.1Cay)2CuO4‐z system with compositions included in the single phase field were synthesized. The carrier density in these samples was varied by controlling the Ca content. The Hall effect and DC resistivity were measured to elucidate the relation between Tc and the carrier density.

Clinopyroxene with Si < AlIV in the join CaFeAISiO6-CaTiAl2O6

1980 ◽  
Vol 43 (331) ◽  
pp. 851-856 ◽  
Author(s):  
Kosuke Onuma ◽  
Masahide Akasaka
Keyword(s):  
Solid Solution ◽  
Solid Solutions ◽  
Phase Field ◽  
Single Phase ◽  
Tetrahedral Sites ◽  
Single Phase Field

SummaryUnusual clinopyroxenes were synthesized in the study of the join CaFeAlSiO6-CaTiAl2O6 in air at I atm. Clinopyroxene solid solution, hibonite solid solution, X-phase, perovskite, and corundum are present, and at subsolidus temperatures the clinopyroxene singlephase field extends up to about 19 wt% CaTiAl2O6. The CaTiAl2O6 component in the clinopyroxene however increases beyond the clinopyroxene single-phase field and attains 23 wt%. These clinopyroxene solid solutions are extremely poor in SiO2 and extremely rich in Al2O3, Fe2O3, and TiO2, and more than half of tetrahedral sites are occupied by AlIV, contravening the aluminium avoidance principle.

High Temperature Deformation Behavior of Beta-Gamma TiAl Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 1531-1536 ◽  
Author(s):  
J.S. Kim ◽  
You Hwan Lee ◽  
Young Won Kim ◽  
Chong Soo Lee
Keyword(s):  
High Temperature ◽  
Deformation Behavior ◽  
Tial Alloy ◽  
Microstructural Analysis ◽  
Processing Condition ◽  
Simulation Method ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Β Phase ◽  
Dynamic Materials

In this study, high-temperature deformation behavior of newly developed beta-gamma TiAl alloys was investigated in the context of the dynamic-materials model (DMM). Processing maps representing the efficiency of power consumption for microstructure evolution were constructed utilizing the results of compression test at temperatures ranging from 1000oC to 1200oC and strain rates ranging from 10-4/s to 102/s and Artificial Neural Network simulation method. With the help of processing map and microstructural analysis, the optimum processing condition for the betagamma TiAl alloy was investigated. The role of β phase was also discussed in this study.

Simulation of Microstructure Evolution and Deformation Behavior for Dual-Phase Steel by Multi-Phase-Field Method and Elastoplastic Finite Element Method

2013 ◽  
Vol 7 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Akinori Yamanaka ◽  
◽  
Tomohiro Takaki ◽  
Keyword(s):  
Finite Element ◽  
Phase Field ◽  
Deformation Behavior ◽  
Volume Fraction ◽  
Simulation Method ◽  
Phase Field Method ◽  
Element Analysis ◽  
Dp Steel ◽  
Α Phase ◽  
Multi Phase

A coupled simulation method is developed by using a Multi-Phase-Field (MPF) method that is recognized as a powerful numerical method for simulating microstructure formation in material and ElastoPlastic Finite Element Analysis (EP-FEA) based on a homogenization method. We apply the developed simulation method to investigate the deformation behavior of DP steel that includes various volume fractions and morphologies of the ferrite (α) phase. To obtain morphological information on the α phase of DP steel, we performed MPF simulation of austenite-to-ferrite (γ → α) transformation during continuous cooling transformation. MPF simulation gives us the digital image of the distribution of the simulated α phase. Furthermore, we model the representative volume element, which describes the DP microstructure, on the basis of the obtained morphology of the α phase, and perform tension-compression testing of DP steel, including the simulated α phase. Through these simulations, it is confirmed that the developed simulation method enables us to clarify the effect of the volume fraction and the configuration of the α phase on macroscopic deformation behavior of DP steel, such as the Bauschinger effect.

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