scholarly journals Local lattice strain around alloying element and martensitic transformation in titanium alloys

2020 ◽  
Vol 321 ◽  
pp. 11009
Author(s):  
M. Morinaga ◽  
H. Yukawa ◽  
M. Yoshino
Keyword(s):  
Martensitic Transformation ◽  
Titanium Alloys ◽  
Strain Energy ◽  
Lattice Strain ◽  
Extreme Case ◽  
Local Strain ◽  
Absolute Temperature ◽  
Lattice Strains ◽  
Local Lattice ◽  
First Time

Local strain is introduced into the lattice around solute atom due to the size mismatch between solute and solvent atoms in alloy. In this study, local lattice strains are calculated for the first time in titanium alloys, using the plane-wave pseudopotential method. As an extreme case, the local lattice strain around a vacancy is also calculated in various bcc, fcc and hcp metals. It is found that the local strain energy is very high in both bcc Ti and bcc Fe, where the martensitic transformation takes place. From a series of calculations, it is shown that the magnitude of the strain energy stored in the local lattice is comparable to the thermal energy, kBT, where kB is the Boltzmann constant and T is the absolute temperature. Therefore, the presence of local lattice strains in alloy could influence the phase stability that varies largely depending on temperatures. For example, the local lattice strain correlates with the martensitic transformation start temperature, Ms, in binary titanium alloys.

Static Multiaxial Fracture Behavior of Graphite Components: A Review of Recent Results

2017 ◽  
Vol 754 ◽  
pp. 35-38 ◽  
Author(s):  
S.M.J. Razavi ◽  
M. Peron ◽  
J. Torgersen ◽  
F. Berto
Keyword(s):  
Strain Energy Density ◽  
Strain Energy ◽  
Fracture Behavior ◽  
Local Strain ◽  
Opening Angle ◽  
Mode Mixity ◽  
Static Tests ◽  
Complete Set ◽  
Tip Radius ◽  
First Time

The problem of mixed mode (I+III) brittle fracture of polycrystalline graphite is investigated systematically here for the first time. The present study considers cylindrical specimens weakened by circumferential notches characterized by different acuities. A new complete set of experimental data is provided considering different geometrical configurations by varying the notch opening angle and the notch tip radius. The multiaxial static tests have been performed considering different values of the mode mixity ratio. A criterion based on the local Strain Energy Density previously applied by the same authors only to pure modes of loading is extended here to the case of tension and torsion loadings applied in combination.

Average and local strain fields in nanocrystals

2019 ◽  
Vol 52 (2) ◽  
pp. 262-273 ◽  
Author(s):  
Shangmin Xiong ◽  
Seung-Yub Lee ◽  
Ismail Cevdet Noyan
Keyword(s):  
Gold Nanoparticles ◽  
Strain Analysis ◽  
Local Strain ◽  
Real Space ◽  
Dynamics Modeling ◽  
Lattice Strains ◽  
Unit Cells ◽  
Local Lattice ◽  
Strain Components ◽  
Average Lattice

This article presents a rigorous and self-consistent comparison of lattice distortion and deformation fields existing in energy-optimized pseudo-spherical gold nanoparticles obtained from real-space and powder diffraction strain analysis techniques. The changes in atomic positions resulting from energy optimization (relaxation) of ideally perfect gold nanoparticles were obtained using molecular dynamics modeling. The relaxed atomic coordinates were then used to compute the displacement, rotation and strain components in all unit cells within the energy-optimized (relaxed) particles. It was seen that all of these terms were distributed heterogeneously along the radial and tangential directions within the nanospheroids. The heterogeneity was largest in the first few atomic shells adjacent to the nanoparticle surface, where the continuity of crystal lattice vectors originating from the interior layers was broken because of local lattice rotations. These layers also exhibited maximum shear and normal strains. These (real-space) strain values were then compared with the average lattice strains obtained by refining the computed diffraction patterns of such particles. The results show that (i) relying solely on full-pattern refinement techniques for lattice strain analysis might lead to erroneous conclusions about the dimensionality and symmetry of deformation within relaxed nanoparticles; (ii) the lattice strains within such relaxed particles should be considered `eigenstrains' (`inherent strains') as defined by Mura [Micromechanics of Defects in Solids, (1991), 2nd ed., Springer]; and (iii) the stress/strain state within relaxed nanoparticles cannot be analyzed rigorously using the constitutive equations of linear elasticity.

Large Deformation and Mechanical Effects of Damage in Aged Duplex Stainless Steel

2010 ◽  
Vol 652 ◽  
pp. 155-160 ◽  
Author(s):  
Lea le Joncour ◽  
Benoit Panicaud ◽  
Andrzej Baczmanski ◽  
Manuel François ◽  
Chedly Braham ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Large Deformation ◽  
Lattice Strain ◽  
Large Plastic Deformation ◽  
Lattice Strains ◽  
Damage Process ◽  
First Time ◽  
Elastic Strains

The lattice strains in large tensile deformations, up to the fracture of the sample were measured using neutron TOF method. For the first time, the range of large deformation was studied measuring lattice strain in the deformation neck and using special correction for macrostress value. It was found that during large plastic deformation the lattice stresses arise almost linearly with the macrostress value. The relaxation of elastic strains in some groups of ferritic grains (corresponding to reflections 211 and 200) can be connected with initiation of damage process in the ferritic phase.

Hydrogen Influence on Martensitic Transformation and Shape Memory Effect in Titanium Alloys

1995 ◽  
Vol 05 (C8) ◽  
pp. C8-1145-C8-1150
Author(s):  
A.A. Ilyin ◽  
M.Yu. Kollerov ◽  
A.M. Mamonov ◽  
A.A. Krastilevsky ◽  
D.Yu. Makarenkov
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Titanium Alloys ◽  
Shape Memory Effect ◽  
Memory Effect

scholarly journals Interfacial Structure of Lattice Mismatched bcc(110)/bcc(110) Transition Metal Superlattices

1993 ◽  
Vol 307 ◽  
Author(s):  
Eric E. Fullerton ◽  
S. M. Mini ◽  
A. S. Bommannavar ◽  
C. H. Sowers ◽  
S. N. Ehrlich ◽  
...  
Keyword(s):  
Lattice Strain ◽  
Structural Model ◽  
Interfacial Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Strains ◽  
The Individual ◽  
Structural Characterizations ◽  
Modulation Wavelength ◽  
Coherent Interfaces

ABSTRACTWe present structural characterizations of a series of sputtered Fe/Nb and V/Nb superlattices by high-angle x-ray diffraction. Diffraction scans were performed with the scattering vector at various angles (χ) with respect to the layers. χ=0° diffraction spectra (normal to the layers) were fitted to a general structural model to determine the (110) lattice strains, interfacial disorder and interdiffusion. χ>0° spectra probe the lattice strain of the individual layers and the in-plane interfacial coherence. Both systems form incoherent interfaces above a critical modulation wavelength (ΛC). At ΛC, the Fe/Nb system undergoes a crystalline-to-amorphous transition while the V/Nb forms in-plane coherent interfaces.

Analysis on the Martensitic Transformation in the Ti-xNb Alloys Using a Phenomenological Theory

2007 ◽  
Vol 124-126 ◽  
pp. 1669-1672 ◽  
Author(s):  
Hi Won Jeong ◽  
Seung Eon Kim ◽  
Chang Yong Jo ◽  
Yong Tae Lee ◽  
Joong Kuen Park
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Titanium Alloys ◽  
Martensitic Transformations ◽  
Phenomenological Theory ◽  
Transition Elements ◽  
Low Elastic Modulus ◽  
Diffraction Peaks

The titanium alloys containing the Nb transition elements have been investigated as the Ni-free shape memory and the biomedical alloys with a low elastic modulus. The mechanical properties of the alloys depended upon the meta-stable phases like the α`, α``, ω. To study the martensitic transformations from the β to α`` or α` the Ti-xNb (x=0 to 40 wt%) alloys were melted into the button type ingots using a VAR, and followed by the water-quenching after the soaking at 1000oC for 2hrs. The crystallography of the martensitic phases in the water-quenched alloys was analyzed using a XRD. The diffraction peaks of the orthorhombic martensites were identified by the crystallographic relationship with the bcc matrix. The lattice parameters of the orthorhombic martensites were varied continuously with the contents of the Nb elements. The martensitic transformations of the alloys were studied using the phenomenological theory of Bowles and Mackenzie.

Specific features of martensitic transformation in titanium alloys

1965 ◽  
Vol 7 (4) ◽  
pp. 233-238 ◽  
Author(s):  
S. G. Fedotov ◽  
E. P. Sinodova
Keyword(s):  
Martensitic Transformation ◽  
Titanium Alloys
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