Fanny Dyment

Measurements of Hf diffusion in α-Ti by HIRBS

Abstract Measurements of the Hf diffusion in α-Ti were made by heavy ions Rutherford backscattering spectrometry (HIRBS). The range of temperature covered was 900–1145 K. The Arrhenius plot is a straight line for the total range of temperature covered with Q = 254 ± 30 kJ / mol and D 0 = (4 ± 2) × 10 −6 m 2 / s . These values are in excellent agreement with previous ones obtained with the RBS technique in the range 823–1023 K. The results suggest that there is no Fe influence on Hf diffusion in α-Ti.

Hafnium diffusion in α-Ti

Abstract The diffusion of Hf in α-Ti has been studied in the temperature range 823–1023 K for the first time using the Rutherford backscattering technique on films 150 A thick deposited on α-Ti samples. The results show that the diffusion coefficients follow a non-regular Arrhenius plot. This behaviour, which has already been observed for α-Zr, is discussed in terms of possible intrinsic and extrinsic diffusional mechanisms.

Au diffusion in α-Ti

The solubility and diffusion of Au in α-Ti have been studied in a 823–1023 K temperature range using the Rutherford backscattering technique. For this purpose we have implanted Au into α-Ti samples. Our results show that the solubility of Au varies between 0.2 and 0.35 at.%. In addition, we found that the diffusion coefficients follow a normal Arrhenius behavior with Q=260 kJ/mol and Do=1.9×10−5 m2/s1. These values are typical for a substitutional diffusion mechanism.

Diffusion study of Sn implanted in α-Ti

Abstract The diffusion of implanted Sn in α-Ti has been studied in the 873–1073 K temperature range using the Rutherford back-scattering spectrometry technique. For this purpose we have implanted Sn in α-Ti samples with two different impurity contents. The measurements in those with a lower level of impurities show that the diffusion coefficients follow a linear Arrhenius plot with the following parameters: The measurements in the samples with higher Fe content indicate that the diffusion mechanism is sensitive to the impurity concentration.

Indium diffusion study in α-titanium

Abstract The diffusion of implanted In α-Ti has been studied in the 823–1073 K temperature range by using the Rutherford backscattering spectrometry (RBS) technique. The measurements show that the diffusion coefficients follow a linear Arrhenius plot: D(T) = (2.0 ± 1.3) × 10−6exp[−(260 ± 40) kJ/mol/RT]m2s−1. The diffusion parameters D0 and Q are typical of a normal substitutional behavior. Comparison of the present and previous published results of impurity diffusion in α-Ti does not show evidence for mass or size effects in the diffusion mechanism.

Ru Self-Diffusion and Ru Diffusion in Al

The self-diffusion of Ru in the temperature range of (1267-1373) K and the Ru diffusion in pure aluminum in the temperature range of (632-873) K is reported. Difficulties were encountered when working with Ru as matrix (its brittleness at room temperature impeded a good sectioning) and they are the reason why only the order of magnitude of the self-diffusion in the small range of temperature studied is given. For Ru diffusion in aluminum, two experimental techniques were used: the conventional serial sectioning with use of a radiotracer, 103Ru, for the highest temperatures and Heavy Ions Rutherford Backscattering Spectrometry (HIRBS) for the lowest ones. The diffusion parameters are: Q = 199.4 kJ/mol and D0 = 4.1x10-2 m2/s. A comparison is made with Ru diffusion behavior in copper and silver.

Diffusion of Pd in α-Ti studied by means of Rutherford back-scattering and channelling techniques

Abstract The diffusion of implanted Pd in α-Ti has been studied in the 723–1073K temperature range by using Rutherford back-scattering and channelling techniques. The measurements show that the diffusion coefficient follows a linear Arrhenius rule D(T) = D 0exp(—Q/RT), where D 0 = (2.0 ± 0.5) × 10−3 m−2s−1 and Q = 264 ± 9 kJmol−1. In addition. channelling experiments performed in the 673–973K temperature interval show that, independent of the annealing temperature, at least 30% of the Pd atoms are at interstitial sites of the Ti matrix. A comparison of the present and previous published data indicates that Pd diffuses more rapidly than substitutional elements but more slowly than the interstitial elements Fe, Co and Mn do. These two features indicate that the diffusion mechanism is not purely substitutional but has a mixed character.

Diffusion along grain and interphase boundaries in alpha Zr and Zr-2.5 wt pct Nb alloy

Diffusion parameters of Cr diffusion along the α/β interphase boundaries of a Zr-2.5 wt pct Nb alloy are presented. The conventional radiotracer technique combined with serial sectioning of the samples was applied. In the Arrhenius plot, it is possible to consider only one straight line (with Q=133 kJ/mol for 615<T<953 K) or two zones (with Q=230 kJ/mol for 773<T<953 K and Q=77 kJ/mol for 615<T<773 K). An analysis is made of these results together with previous data concerning diffusion along short circuits paths in α-Zr (grain boundaries) and Zr-2.5 wt pct Nb (interphase boundaries): Zr and Nb as the alloy component elements and Ni, Fe, and Co as other relevant impurities. Different mechanisms are proposed: a vacancy mechanism for Zr and Nb and an interstitial-like mechanism for the impurities, for both kind of boundaries. The influence on diffusion and the estimated values of the impurities segregation in the α phase are discussed in the work.

Grain Boundary Diffusion and Segregation of Co and Cr in Zr-Based Alloys

51Cr and 60Co diffusion along grain boundary (GB) in polycrystalline Zr and -Zr-20%Nb were measured by means of the radiotracer technique in an overall temperature range [380-1000] K. The use of Harrison´s C and B kinetics resulted in direct data of the GB diffusivity (Dgb) and the apparent GB diffusivity (Pgb). The analyzed temperatures involved those of power reactors service. The GB segregation factors s were determined or evaluated in the limit of very dilute solute concentration.