Diffusion in &amp;alpha;-Ti and Zr

Pérez, Rocío L.; Nakajima, Hideo; Dyment, F.

doi:10.2320/matertrans.44.2

Cited by 141 publications

(78 citation statements)

References 49 publications

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“…The Fe-Ni regions are frequently the larger of the two within an SPP cluster, suggesting that Fe-Ni SPPs act as nucleation sites for Fe-Cr SPPs. This is supported by the respective diffusivities of the elements in α-Zr Fe > Ni >> Cr [37] such that Fe-Ni SPPs nucleate first. All of the Fe-Ni SPPs studied in the present work contained no Cr, suggesting more chemical homogeneity in Fe-Ni in contrast to FeCr SPPs.…”

Section: Spp Dissolution 411 Internal Spp Diffusional Capacity and mentioning

confidence: 52%

“…At 2.3 dpa, the very edge of the Fe/Ni SPPs seems to have greater Ni depletion relative to Fe, resulting in a slight skew to the right for the histograms of Figure 6b. This is unexpected as the diffusivity of Fe is slightly greater than that of Ni in α-Zr [37]. However, at higher irradiation doses 4.7 and 7.0 dpa, the Fe/Ni at the periphery approaches unity, supporting the similar matrix diffusivities of Fe and Ni and suggesting that their diffusivity within the Fe-Ni SPP is not the same as that in α-Zr.…”

Section: Spp Dissolution and Amorphisationmentioning

confidence: 54%

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Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy

Harte

Topping

Frankel

et al. 2017

Journal of Nuclear Materials

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A. Harte et al., Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy J. Nucl. Mater. Accepted Jan. 2017 Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy (Fe,Ni). This is accomplished through ultra-high spatial resolution scanning transmission electron microscopy and the use of energy-dispersive X-ray spectroscopic methods. Fe-depletion is observed from both SPP types after irradiation with both irradiative species, but is heterogeneous in the case of Zr(Fe,Cr) 2 , predominantly from the edge region, and homogeneously in the case of Zr 2 (Fe,Ni). Further, there is evidence of a delay in the dissolution of the Zr 2 (Fe,Ni) SPP with respect to the Zr(Fe,Cr) 2 . As such, SPP dissolution results in matrix supersaturation with solute under both irradiative species and proton irradiation is considered well suited to emulate the effects of neutron irradiation in this context. The mechanisms of solute redistribution processes from SPPs and the consequences for irradiation-induced growth phenomena are discussed.

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Section: Spp Dissolution 411 Internal Spp Diffusional Capacity and mentioning

confidence: 52%

Section: Spp Dissolution and Amorphisationmentioning

confidence: 54%

Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy

Harte

Topping

Frankel

et al. 2017

Journal of Nuclear Materials

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“…The diffusion coefficient for self-diffusion increases by adding a small amount of impurity to ultra-high purity Ti with an HCP structure, but the increase becomes large at lower temperatures and the slope of an Arrhenius plot therefore decreases and becomes small. Perez, Nakajima, and Dyment (2003) reviewed that the addition of Co to α-Ti increases the diffusion coefficient by more than an order of magnitude and proposed the mechanisms of ultra-fast diffusion. However, the enhancement of self-diffusion of α-Ti due to the addition of a very small amount of impurity has not been explained.…”

Section: Journal Of Materials Science Researchmentioning

confidence: 99%

Verification of Equation for Evaluating Dislocation Density during Steady-state Creep of Metals

Tamura¹

2017

JMSR

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Ninety-two sets of observed dislocation densities for crept specimens of 21 types of ferritic/martensitic and austenitic steels, Al, W, Mo, and Mg alloys, Cu, and Ti including germanium single crystals were collected to verify an equation for evaluating the dislocation density during steady-state creep proposed by Tamura and Abe (2015). The activation energy, , activation volume, , and Larson-Miller constant, , were calculated from the creep data. Using these parameter constants, the strain rate, and the temperature dependence of the shear modulus, a correction term, , was back-calculated from the observed dislocation density for each material. is defined in the present paper as a function of the temperature dependences of both the shear modulus and pre-exponential factor of the strain rate. The values of range from −394 to 233 kJmol and average 2.1 kJmol , which is a value considerably lower than the average value of (410.4 kJmol ), and values of are mainly within the range from 0 to 50 kJmol . The change in Gibbs free energy, ∆ , for creep deformation is obtained using the calculated value of , and the empirical relation ∆ ≅ ∆ is found, where ∆ is the change in Gibbs free energy for self-diffusion of the main componential element of each material. Experimental data confirm the validity of the evaluation equation for the dislocation density.

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“…Co is known to be a so-called "ultrafast diffuser" in the crystalline bulk of CG -Ti [132]. It occurred that Co is an ultrafast diffuser in grain boundaries of CG -Ti, too.…”

mentioning

confidence: 99%

Grain boundaries in ultrafine grained materials processed by severe plastic deformation and related phenomena

Sauvage

Wilde

Divinski

et al. 2012

Materials Science and Engineering: A

489

219

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Grain boundaries in ultrafine grained (UFG) materials processed by severe plastic deformation (SPD) are often called "non-equilibrium" grain boundaries. Such boundaries are characterized by excess grain boundary energy, presence of long range elastic stresses and enhanced free volumes. These features and related phenomena (diffusion, segregation, etc.) have been the object of intense studies and the obtained results provide convincing evidence of the importance of a non-equilibrium state of high angle grain boundaries for UFG materials with unusual properties. The aims of the present paper are first to give a short overview of this research field and then to consider tangled, yet unclear issues and outline the ways of oncoming studies. A special emphasis is given on the specific structure of grain boundaries in ultrafine grained materials processed by SPD, on grain boundary segregation, on interfacial mixing linked to heterophase boundaries and on grain boundary diffusion. The connection between these unique features and the mechanical properties or the thermal stability of the ultrafine grained alloys is also discussed.

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Diffusion in α-Ti and Zr

Cited by 141 publications

References 49 publications

Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy

Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy

Verification of Equation for Evaluating Dislocation Density during Steady-state Creep of Metals

Grain boundaries in ultrafine grained materials processed by severe plastic deformation and related phenomena

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