Grain Boundary Diffusion in Cation-Doped Superplastic 3Y-TZP

2006 ◽  
Vol 45 ◽  
pp. 1626-1631
Author(s):  
Marek Boniecki ◽  
Rafał Jakieła ◽  
Zdzislaw Librant ◽  
Wladyslaw Wesolowski ◽  
Danuta Dabrowska ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Thin Films ◽  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Tetragonal Zirconia ◽  
Grain Boundary Diffusion ◽  
Depth Profiles ◽  
Secondary Ion

The superplastic flow in tetragonal zirconia polycrystals stabilised 3mol% Y2O3 (3YTZP) is strongly affected by the dopant cations, which segregate at the grain boundary. It is proposed that this flow is controlled by grain boundary diffusion of Zr4+ ions and therefore the dopant cations should change the grain boundary diffusion. In order to prove this thesis the measurements of grain boundary diffusion coefficients were made using Hf4+ ions as tracer. Zirconia samples were doped with 1mol% of Al2O3, SiO2, MgO, MgAl2O4, GeO2 and TiO2. The tracer was deposited on the surface of the zirconia specimens by placing several drops of hafnium nitrate and then drying at 373 K. In this way, thin films of HfO 2 were obtained. The samples were heated in the range 1553 – 1773 K for 1 to 24 h. The concentration versus depth profiles were measured using secondary ion mass spectrometry (SIMS). Calculated hence grain boundary diffusion coefficients were several times bigger for doped samples than for pure 3Y-TZP samples.

Study of Fe Diffusion in Cr2O3 by Secondary Ion Mass Spectrometry

2005 ◽  
Vol 237-240 ◽  
pp. 940-945
Author(s):  
Antônio Claret Soares Sabioni ◽  
Anne Marie Huntz ◽  
F. Silva ◽  
François Jomard
Keyword(s):  
Mass Spectrometry ◽  
Activation Energy ◽  
Grain Boundary ◽  
Boundary Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Bulk Diffusion ◽  
Grain Boundary Diffusion ◽  
Iron Diffusion ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Chromia protective layers are used to prevent corrosion by oxidation of many alloys, such as the stainless steels, for instance. To check if chromia is a barrier to the outward diffusion of iron in these alloys, iron diffusion in chromia was studied in both polycrystals and oxide films formed by oxidation of Ni-30Cr alloy in the temperature range 700-1100°C at an oxygen pressure equal to 10-4 atm. An iron film of about 70 nm thick was deposited on the chromia surface, and after the diffusing treatment, the iron depth profiles were established by secondary ion mass spectrometry (SIMS). Using a solution of the Fick’s second law for diffusion from a thick film, effective or bulk diffusion coefficients were determined in a first penetration domain. Then, Le Claire’s and Hart’s models allowed both the bulk diffusion coefficient and the grain boundary diffusion parameter (aDgbd) to be obtained in a second penetration domain. Iron bulk and grain boundary diffusion does not vary significantly according to the nature-microstructure of chromia. The activation energy of grain boundary diffusion is at least equal or even greater than the activation energy of bulk diffusion, probably on account of segregation phenomena. Iron diffusion was compared to cationic self-diffusion and related to the protective character of chromia.

Approximate Solutions of Grain Boundary Diffusion in Thin Films in the B2 Regime

2005 ◽  
Vol 237-240 ◽  
pp. 206-211
Author(s):  
P. Fielitz ◽  
Günter Borchardt
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Boundary Diffusion ◽  
Approximate Solutions ◽  
Average Concentration ◽  
Grain Boundary Diffusion ◽  
The Other ◽  
Depth Profiles ◽  
Complicated Form ◽  
Concentration Depth Profiles

Exact mathematical solutions of the grain boundary diffusion equation in thin films have generally a complicated form, which is too cumbersome for the evaluation of experimental average concentration depth profiles obtained by sectioning techniques. On the other hand the accuracy of the exact solutions is not necessary for practical purposes so that it is useful to derive sufficiently accurate approximate solutions. We propose a method to derive such solutions for a thin film if the grain boundary diffusion is in the B2 regime. These solutions are derived for different diffusion sources.

Simultaneous Measurements of Lattice and Grain Boundary Diffusion Coefficients via 2-Dimensional Simulations

2010 ◽  
Vol 297-301 ◽  
pp. 978-983
Author(s):  
Ivan Blum ◽  
Alain Portavoce ◽  
Dominique Mangelinck ◽  
Jean Bernardini ◽  
Khalid Hoummada ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
The Finite Element Method ◽  
Measure Concentration ◽  
Dimensional Diffusion ◽  
Transmission Electron ◽  
Before And After ◽  
Secondary Ion

A method is presented to measure lattice and grain boundary diffusion coefficients using secondary ion mass spectroscopy and 2-dimensional diffusion simulations. SIMS is used to measure concentration profiles of implanted species before and after annealing. The as-implanted concentration profile is used as the initial condition for 2-dimensional diffusion simulations using the finite element method. The geometry of the simulation is based on the microstructure of the sample observed by transmission electron microscopy. Both lattice and grain boundary diffusion are simulated. The final 2-dimensional concentration distribution is projected on the depth axis to obtain a simulated depth profile. The diffusion coefficients are adjusted to fit the profiles measured after annealing. We find that this method allows to determine simultaneously and independently the lattice and grain boundary diffusion coefficients from the same profiles. This method is used to measure the diffusion coefficients of As in polycrystalline Ni2Si thin films. The simulations are found to fit the measured profiles with accuracy. The coefficients are measured between 550 and 700°C. An activation energy ratio Qgb/Qv is found greater than one. This result is corroborated by existing data in silicides and is compared to results in other materials for discussion.

An investigation of cobalt oxide based nanocrystalline thin films by secondary ion mass spectrometry

2001 ◽  
Vol 15 (17) ◽  
pp. 1621-1624 ◽  
Author(s):  
Simona Barison ◽  
Davide Barreca ◽  
Sergio Daolio ◽  
Monica Fabrizio ◽  
Eugenio Tondello
Keyword(s):  
Mass Spectrometry ◽  
Thin Films ◽  
Cobalt Oxide ◽  
Secondary Ion Mass Spectrometry ◽  
Ion Mass Spectrometry ◽  
Secondary Ion ◽  
Nanocrystalline Thin Films
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