scholarly journals Study on Phase Transformation Orientation Relationship of HCP-FCC during Rolling of High Purity Titanium

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1164
Author(s):  
Fengmei Bai ◽  
Qingliang Zhu ◽  
Jiaming Shen ◽  
Zhihan Lu ◽  
Liqiang Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Orientation Relationship ◽  
Pole Figure ◽  
High Purity ◽  
Transformation Matrix ◽  
Thin Strip ◽  
Face Centered Cubic ◽  
Fcc Phase ◽  
Purity Titanium

High purity titanium (Ti) thin strip was prepared by rolling with large deformation and was characterized by the means of Transmission Electron Microscopy (TEM), selected area diffraction (SAED) pattern, high-resolution (HRTEM) analysis, as well as Transmission Kikuchi Diffraction (TKD). It is found that there are face-centered cubic (FCC) Ti laths formed within the matrix of hexagonal close packing (HCP) Ti. This shows that the HCP-FCC phase transition occurred during the rolling, and a specific orientation relationship (OR) between HCP phase and FCC phase obeys ⟨0001⟩α// ⟨001⟩FCC and {100}α//{110}FCC. The ORs of HCP-FCC phase transition are deeply studied by TKD pole figure and phase transformation matrix. It is found that the derived results via pole figure and transformation matrix are equivalent, and are consistent with TEM-SAED analysis results, which proves that these two methods can effectively characterize the ORs of HCP-FCC phase transition and predict possible FCC phase variants.

Intergranular Strain and Phase Transformation in a Cobalt-Based Superalloy

2006 ◽  
Vol 524-525 ◽  
pp. 893-898 ◽  
Author(s):  
Michael L. Benson ◽  
A.D. Stoica ◽  
Peter K. Liaw ◽  
Hahn Choo ◽  
T.A. Saleh ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Strain Analysis ◽  
Face Centered Cubic ◽  
Macroscopic Stress ◽  
Intergranular Strain ◽  
Lattice Strains ◽  
The Face ◽  
Face Centered ◽  
Fcc Phase ◽  
In Situ Neutron Diffraction

ULTIMET® alloy, a cobalt-based superalloy with good corrosion and wear resistant properties, exhibits a deformation-induced phase transformation from the face-centered-cubic (FCC) phase to the hexagonal-close-packed (HCP) phase. The HCP phase formation during monotonic tensile loading was investigated using in-situ neutron diffraction. The HCP phase is first observed at a stress level of 810 MPa, which is well beyond macroscopic yielding. Strain analysis is performed on the FCC phase diffraction data in order to relate the lattice-strain development with the evolution of the new HCP phase. A method of calculating the effective macroscopic stress associated with the measured lattice strains is presented here. The effective stress can then be compared to the applied macroscopic stress in order to draw conclusions about the load-partitioning behavior of the material as a new phase develops.

Is there a hexagonal-close-packed (hcp) → face-centered-cubic (fcc) allotropic transformation in mechanically milled Group IVB elements?

2009 ◽  
Vol 24 (11) ◽  
pp. 3454-3461 ◽  
Author(s):  
Uma M.R. Seelam ◽  
Gagik Barkhordarian ◽  
Challapalli Suryanarayana
Keyword(s):  
Phase Transformation ◽  
Critical Analysis ◽  
High Energy ◽  
Argon Atmosphere ◽  
Face Centered Cubic ◽  
Allotropic Transformation ◽  
Nanocrystalline State ◽  
Hexagonal Close Packed ◽  
Face Centered ◽  
Fcc Phase

Allotropic hexagonal-close-packed (hcp) → face-centered-cubic (fcc) transformations were reported in Group IVB elements titanium (Ti), zirconium (Zr), and hafnium (Hf) subjected to mechanical milling in a high-energy SPEX shaker mill. Although the transformation was observed in powders milled under regular conditions, no such phase transformation was observed when the powders were milled in an ultrahigh purity environment by placing the powder in a milling container under a high-purity argon atmosphere, which was in turn placed in an argon-filled glove box for milling. From a critical analysis of the results, it was concluded that the hcp → fcc phase transformation was, at least partially, due to pick-up of interstitial impurities by the powder during milling of these powders to the nanocrystalline state.

scholarly journals Derived crystal structure of martensitic materials by solid–solid phase transformation

2020 ◽  
Vol 76 (4) ◽  
pp. 521-533 ◽  
Author(s):  
Mostafa Karami ◽  
Nobumichi Tamura ◽  
Yong Yang ◽  
Xian Chen
Keyword(s):  
Crystal Structure ◽  
Phase Transformation ◽  
Orientation Relationship ◽  
Solid Phase ◽  
Lattice Parameters ◽  
Orthorhombic Symmetry ◽  
Face Centered Cubic ◽  
X Ray ◽  
Solid Phase Transformation ◽  
Martensitic Materials

A mathematical description of crystal structure is proposed consisting of two parts: the underlying translational periodicity and the distinct atomic positions up to the symmetry operations in the unit cell, consistent with the International Tables for Crystallography. By the Cauchy–Born hypothesis, such a description can be integrated with the theory of continuum mechanics to calculate a derived crystal structure produced by solid–solid phase transformation. In addition, the expressions for the orientation relationship between the parent lattice and the derived lattice are generalized. The derived structure rationalizes the lattice parameters and the general equivalent atomic positions that assist the indexing process of X-ray diffraction analysis for low-symmetry martensitic materials undergoing phase transformation. The analysis is demonstrated in a CuAlMn shape memory alloy. From its austenite phase (L21 face-centered cubic structure), it is identified that the derived martensitic structure has orthorhombic symmetry Pmmn with the derived lattice parameters a d = 4.36491, b d = 5.40865 and c d = 4.2402 Å, by which the complicated X-ray Laue diffraction pattern can be well indexed, and the orientation relationship can be verified.

Diffraction Stress Analysis of Fiber Textured Ti Thin Films Undergoing hcp - fcc Phase Transformation

2013 ◽  
Vol 768-769 ◽  
pp. 257-263
Author(s):  
Jay Chakraborty
Keyword(s):  
Thin Films ◽  
Phase Transformation ◽  
Stress Analysis ◽  
Group Method ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Hexagonal Close Packed ◽  
Face Centered ◽  
Fcc Phase ◽  
Ti Films

X-ray diffraction stress analysis by crystallite group method (CGM) has been employed in case of simultaneously strong and sharp fiber textured Ti thin films. These Ti films exhibit thickness dependent hcp-fcc phase transformation [Ref. 1]. Diffraction stress analysis has also been attempted by d-sin2 method for strongly textured face centered cubic (fcc) and hexagonal close packed (hcp) Ti phases. For hcp Ti phase, the results of stress analysis by CGM are compared with those obtained from d-sin2 method. It is found that the stress values in hcp Ti phases obtained from CGM considerably differ from the stresses obtained from d-sin2 method in some of the Ti films. Observed differences have been explained and possible sources of errors in d-sin2 method and CGM stress analysis have been discussed.

scholarly journals Stability and equation of state of face-centered cubic and hexagonal close packed phases of argon under pressure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agnès Dewaele ◽  
Angelika D. Rosa ◽  
Nicolas Guignot ◽  
Denis Andrault ◽  
João Elias F. S. Rodrigues ◽  
...  
Keyword(s):  
Equation Of State ◽  
Single Crystal ◽  
Single Crystal Sample ◽  
Moderate Pressure ◽  
Face Centered Cubic ◽  
Experimental Conditions ◽  
Crystal Sample ◽  
Hexagonal Close Packed ◽  
Face Centered ◽  
Fcc Phase

AbstractThe compression of argon is measured between 10 K and 296 K up to 20 GPa and and up to 114 GPa at 296 K in diamond anvil cells. Three samples conditioning are used: (1) single crystal sample directly compressed between the anvils, (2) powder sample directly compressed between the anvils, (3) single crystal sample compressed in a pressure medium. A partial transformation of the face-centered cubic (fcc) phase to a hexagonal close-packed (hcp) structure is observed above 4.2–13 GPa. Hcp phase forms through stacking faults in fcc-Ar and its amount depends on pressurizing conditions and starting fcc-Ar microstructure. The quasi-hydrostatic equation of state of the fcc phase is well described by a quasi-harmonic Mie–Grüneisen–Debye formalism, with the following 0 K parameters for Rydberg-Vinet equation: $$V_0$$ V 0 = 38.0 Å$$^3$$ 3 /at, $$K_0$$ K 0 = 2.65 GPa, $$K'_0$$ K 0 ′ = 7.423. Under the current experimental conditions, non-hydrostaticity affects measured P–V points mostly at moderate pressure ($$\le$$ ≤ 20 GPa).

scholarly journals Pressure-Induced Structural Phase Transition and Metallization in Ga2Se3 up to 40.2 GPa under Non-Hydrostatic and Hydrostatic Environments

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 746
Author(s):  
Meiling Hong ◽  
Lidong Dai ◽  
Haiying Hu ◽  
Xinyu Zhang
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
High Pressure ◽  
Phase Transformation ◽  
Transport Properties ◽  
Electrical Transport ◽  
Structural Phase ◽  
Structure Evolution ◽  
Systematic Research ◽  
Electrical Transport Properties

A series of investigations on the structural, vibrational, and electrical transport characterizations for Ga2Se3 were conducted up to 40.2 GPa under different hydrostatic environments by virtue of Raman scattering, electrical conductivity, high-resolution transmission electron microscopy, and atomic force microscopy. Upon compression, Ga2Se3 underwent a phase transformation from the zinc-blende to NaCl-type structure at 10.6 GPa under non-hydrostatic conditions, which was manifested by the disappearance of an A mode and the noticeable discontinuities in the pressure-dependent Raman full width at half maximum (FWHMs) and electrical conductivity. Further increasing the pressure to 18.8 GPa, the semiconductor-to-metal phase transition occurred in Ga2Se3, which was evidenced by the high-pressure variable-temperature electrical conductivity measurements. However, the higher structural transition pressure point of 13.2 GPa was detected for Ga2Se3 under hydrostatic conditions, which was possibly related to the protective influence of the pressure medium. Upon decompression, the phase transformation and metallization were found to be reversible but existed in the large pressure hysteresis effect under different hydrostatic environments. Systematic research on the high-pressure structural and electrical transport properties for Ga2Se3 would be helpful to further explore the crystal structure evolution and electrical transport properties for other A2B3-type compounds.

Effects of α–γ–α Phase Transformation on the ∑3 Boundaries in High-Purity Iron

2021 ◽  
Author(s):  
Syed Ejaz Hussain ◽  
Weiguo Wang ◽  
Xinfu Gu ◽  
Yunkai Cui ◽  
Ahua Du ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Purity ◽  
Α Phase ◽  
Purity Iron ◽  
High Purity Iron

scholarly journals Solid Form and Phase Transformation Properties of Fexofenadine Hydrochloride during Wet Granulation Process

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 802
Author(s):  
Suye Li ◽  
Hengqian Wu ◽  
Yanna Zhao ◽  
Ruiyan Zhang ◽  
Zhengping Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Water Content ◽  
Scale Up ◽  
Small Scale ◽  
Dissolution Behavior ◽  
Wet Granulation ◽  
Water Addition ◽  
Granulation Process ◽  
And Performance

The quality control of drug products during manufacturing processes is important, particularly the presence of different polymorphic forms in active pharmaceutical ingredients (APIs) during production, which could affect the performance of the formulated products. The objective of this study was to investigate the phase transformation of fexofenadine hydrochloride (FXD) and its influence on the quality and performance of the drug. Water addition was key controlling factor for the polymorphic conversion from Form I to Form II (hydrate) during the wet granulation process of FXD. Water-induced phase transformation of FXD was studied and quantified with XRD and thermal analysis. When FXD was mixed with water, it rapidly converted to Form II, while the conversion is retarded when FXD is formulated with excipients. In addition, the conversion was totally inhibited when the water content was <15% w/w. The relationship between phase transformation and water content was studied at the small scale, and it was also applicable for the scale-up during wet granulation. The effect of phase transition on the FXD tablet performance was investigated by evaluating granule characterization and dissolution behavior. It was shown that, during the transition, the dissolved FXD acted as a binder to improve the properties of granules, such as density and flowability. However, if the water was over added, it can lead to the incomplete release of the FXD during dissolution. In order to balance the quality attributes and the dissolution of granules, the phase transition of FXD and the water amount added should be controlled during wet granulation.

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