Ti and Ni Grain Boundary Diffusion in B2 NiTi Compound

2015 ◽  
Vol 363 ◽  
pp. 137-141 ◽  
Author(s):  
Dan Dan Liu ◽  
Jochen Fiebig ◽  
Martin Peterlechner ◽  
Simon Trubel ◽  
Matthias Wegner ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Boundary Structure ◽  
Segregation Coefficient ◽  
Radiotracer Technique ◽  
Grain Boundary Structure ◽  
Boundary Diffusion Coefficient ◽  
Boundary Triple ◽  
Boundary Width

The radiotracer technique was used to measure the grain boundary diffusion of44Ti and63Ni in slightly Ni-rich polycrystalline NiTi compound in the temperature range of 673 - 923 K. The temperature dependence of the grain boundary triple productP(P=sδDgb,sis the segregation coefficient,δis the grain boundary width, andDgbis the grain boundary diffusion coefficient) for Ti and Ni was determined. The triple products of both Ti and Ni grain boundary diffusion in NiTi reveal a unique behavior with significant deviations from an Arrhenius-type dependence. Probable evolution of the grain boundary structure with temperature was used to interpret this phenomenon.

Grain Boundary Diffusion and Segregation in the Solid State Phase Transformations

1998 ◽  
Vol 527 ◽  
Author(s):  
E. Rabkin ◽  
W. Gust
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Solute Diffusion ◽  
Apparent Difference ◽  
Impurity Drag ◽  
The Difference ◽  
Boundary Width ◽  
Dynamic Segregation

ABSTRACTWe consider the problem of solute diffusion and segregation in the grain boundaries moving during a phase transformation in the framework of Cahn's impurity drag model. The concept of a dynamic segregation factor for the diffusion along moving grain boundaries is introduced. The difference between static and dynamic segregation factors may cause the apparent difference of the triple product of the segregation factor, grain boundary width and grain boundary diffusion coefficient for stationary and moving grain boundaries. The difference between static and dynamic segregation is experimentally verified for the Cu(In)-Bi system, for which the parameters of static segregation are well-known. It is shown that the complications associated with the dynamic segregation may be avoided during the study of the discontinuous ordering reaction. From the kinetics of this reaction, the activation energy of the grain boundary self-diffusion can be determined.

Pressure, temperature, water content, and oxygen fugacity dependence of the Mg grain-boundary diffusion coefficient in forsterite

2018 ◽  
Vol 103 (9) ◽  
pp. 1354-1361 ◽  
Author(s):  
Hongzhan Fei ◽  
Sanae Koizumi ◽  
Naoya Sakamoto ◽  
Minako Hashiguchi ◽  
Hisayoshi Yurimoto ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Water Content ◽  
Oxygen Fugacity ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Boundary Diffusion Coefficient ◽  
Temperature Water

Measurement of the Impurity Diffusivity of Cu in Fe by Laser Induced Breakdown Spectrometry

2005 ◽  
Vol 237-240 ◽  
pp. 266-270 ◽  
Author(s):  
Chan Gyu Lee ◽  
Jung Han Lee ◽  
Byeong Seon Lee ◽  
Yong Ill Lee ◽  
Toshitada Shimozaki ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Volume Diffusion ◽  
Diffusion Mechanism ◽  
Grain Boundary Diffusion ◽  
Impurity Diffusion ◽  
Boundary Diffusion Coefficient ◽  
Laser Induced Breakdown ◽  
Good Agreement

The impurity diffusion coefficients of Cu in Fe have been determined in the temperature range of 1073 - 1163 K by means of Laser Induced Breakdown Spectrometry (LIBS). The volume diffusion coefficients for Cu impurity diffusion in a-iron found in this work are in good agreement with the previously published result. The grain boundary diffusion coefficient gb D s d was also calculated using the volume diffusivity and processing the tails of the measured profiles. The values of the activation energy for volume and grain boundary diffusion were approximately 280 and 161 kJmol-1, respectively. This indicates the possibility of a monovacancy diffusion mechanism in case of volume diffusion. The results for the diffusion coefficients are Dv= 2.2 ×10-2exp(-280 kJmol-1/RT) m2s-1 and gb D s d = 2.6 ×10-11exp(-161 kJmol-1/RT) m3s-1.

scholarly journals ANALYSIS USING ELECTROLYTIC LAYER STRIPPING TO DETERMINE THE PARAMETERS OF GRAIN-BOUNDARY DIFFUSION OF COBALT IN POLYCRYSTALLINE NICKEL

2020 ◽  
Vol 12 (4) ◽  
pp. 62-69
Author(s):  
A.Yu. Istomina ◽  
◽  
E.V. Osinnikov ◽  
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Residual Activity ◽  
Grain Boundary Diffusion ◽  
Reference Source ◽  
Diffusion Annealing ◽  
Layer By Layer ◽  
Polycrystalline Nickel ◽  
Radiometric Analysis ◽  
Boundary Triple

A technique for layer-by-layer radiometric analysis using electrolytic layer stripping to determine the parameters of grain-boundary diffusion of cobalt in polycrystalline nickel has been developed. The aim of the work is to develop a complete technological cycle of layer-by-layer radiometric analysis, to select the optimal electrolyte composition for nickel and the conditions for conducting an experiment to remove metal layers with their thickness of 20–200 nm. The studies have been carried out on nickel of nominal purity of 99,98 %. The stabilizing heat treatment of the samples is carried out at a pressure of 10–5 Pa for 2 hours at a temperature of 1273 K. Diffusion annealing is carried out at a pressure of 10–9 Pa in the temperature range of 623–1173 K for 5–30 hours. Concentration profiles have been measured by parallel stripping of layers, which are obtained by electrolytic polishing in a solution based on nickel sulfamate, followed by weighing the sample on a high-precision analytical balance. The difference in weight before and after removal of the layers is used to further calculate the thickness of the removed layers and, as a consequence, the penetration depth of the diffusing. The residual activity of the sample is measured using a digital gamma spectrometer with a NaI (Tl) detector. Before carrying out the experiments, a reference source with a previously known activity has been made to take into account the correction factor due to the radioactive decay of 57Co. The specific layer activity is calculated from the integral remainder of the 122,14 keV line using the Gruzin method. Based on the proposed technique, it is possible to determine the parameters of grain boundary diffusion, such as the diffusion coefficient of grain boundary, triple product and segregation coefficient.

Systematics of Grain Boundary Diffusion and Solute Segregation in Copper Poly- and Bicrystals

2008 ◽  
Vol 273-276 ◽  
pp. 168-175 ◽  
Author(s):  
Sergiy V. Divinski
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Copper Matrix ◽  
Solute Concentration ◽  
Solute Segregation ◽  
Grain Boundary Diffusion ◽  
Dilute Solution ◽  
Boundary Width ◽  
Dilute Limit ◽  
Boundary Diffusivity

Recent results on radiotracer grain boundary diffusion of different solutes in the same high-purity polycrystalline copper are reviewed. The measurements were performed in extended temperature intervals satisfying Harrison’s B and C regime conditions at higher and lower temperatures, respectively. In the B regime, the triple product P = sδDgb was determined, while the grain boundary diffusivity Dgb was directly measured in the C regime (s is the segregation factor and δ the grain boundary width). Consequently, the segregation of different solutes in the copper matrix was determined for the true dilute limit conditions. The results on grain boundary diffusion and segregation are analysed in relation to the solute – solvent binding and solute – vacancy interaction in the bulk and in the grain boundaries. By increasing amount of the applied radiotracer the effect of solute concentration on grain boundary diffusion can thoroughly be examined. Grain boundary diffusion experiments on well-characterised bicrystals have been shown to be most suitable for such a study. In a radiotracer experiment, the complete solute segregation isotherm can be measured beginning already from a dilute solution in both, bulk and grain boundary.

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