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

Abstract

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.

Measurements of diffusion coefficients in solids by means of LIBS combined with direct sectioning

“…All these effects, that happen when successive laser shots are delivered onto the same spatial point on the sample surface, are very well known and were also observed in the previous works [5,6] given origin to a convoluted signal since a fraction of the material coming from previous shot is unavoidable mixed in the signal of the next one.…”

“…We began the measurements applying the method reported in the literature [5,6] used in order to get diffusion profiles. The laser beam impinges perpendicular to the deposited surface, parallel to the diffusion direction.…”

“…[5,6] in what we call the single crater mode (see Section 4.1 further on), the goal of the present work, after analyzing several alternatives, is to improve the experimental set ups by combining direct sectioning via a precision grinder with LIBS as analysis tool in order to measure non-radioactive diffusant concentrations layer by layer.…”

Diffusivity and Solubility of Cu in a Reactor Pressure Vessel Steel Studied by Atom Probe Tomography

“…Typically, the diffusion coefficient of Cu in pure Fe has been determined using Cu-Fe diffusion couples, based on activity measurement, 5,6) electron probe microanalysis 7) and laser-induced breakdown spectrometry. 8) However, since the spatial resolution of these techniques is only about 23 µm, only long-range diffusion can be studied. Thus, measurements have been carried out on specimens subjected to temperatures of ²690°C, which are much higher than the typical operating temperatures of about 300°C for light water reactors.…”

Diffusivity and Solubility of Cu in a Reactor Pressure Vessel Steel Studied by Atom Probe Tomography

“…Typically, the diffusion coefficient of Cu in pure Fe has been determined using CuFe diffusion couples, based on activity measurement, 5,6) electron probe microanalysis, 7) and laser-induced breakdown spectrometry. 8) However, since the spatial resolution of these techniques is only about 23 µm, only long-range diffusion can be studied. Thus, measurements have been carried out on samples subjected to temperatures of ²690°C, which are much higher than the typical operating temperatures of about 300°C for light water reactors.…”