Quantitative analysis of aluminium alloys using SIMS

C. J. Simensen; U. Södervall

doi:10.3139/ijmr-2002-0059

Article

Quantitative analysis of aluminium alloys using SIMS

C. J. Simensen and U. Södervall

Published/Copyright: January 4, 2022

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From the journal International Journal of Materials Research Volume 93 Issue 4

Abstract

A quantitative method for analysis of aluminium alloys using secondary-ion mass spectroscopy has been tested. The sensitivity factor, S_x/Al, for several elements (x) was determined using homogenised Al materials. Also other Al alloys were analysed using almost identical instrumental conditions. It was found that since the materials investigated contained much Fe and Mg, they contributed with molecular interferences when measuring Ti and Ni. The results showed that while keeping constant the analytical parameters, it was possible to use sensitivity factors S_x/Al with a good accuracy for quantification of the elements which were mainly solved in the matrix. The results indicated that the metal was still slightly inhomogeneous in several elements even after annealing at 550 °C for one week. Another important factor is that the emission spectrometer has a high relative standard deviation for the analysis below 5 wt.ppm. This resulted in variations in the calculated sensitivity factor for elements like Na and Ca determined for different materials.

The new method was used for calculating concentration profiles of elements in Al materials as a function of the sputtering depth. Samples of alloy AA5182 were homogenised for one week at 5 different temperatures between 450 and 580 °C. The solubility of K, Na, and B in Al was determined. They were of the order 0.2 wt.ppm Na, 0.3 wt.ppm B and 0.04 wt.ppm K at 550 °C.

Keywords: Aluminium alloys; SIMS; Solid solution; Microstructure

Dr. C. J. Simensen P. O. Box 124 Blindern, 0314-Oslo, Norway Tel.: +47 2206 7791 Fax: +47 2206 7350

The authors will express their gratitude to Hydro Aluminium as and Elkem Aluminium ANS for their financial support.

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Appendix

Determination of the sensitivity factors by means of particles

Assume that the alloy consists of Al matrix and an intermetallic phase X with a predetermined chemical composition. (The phase is either a stochiometric phase or the concentration has been determined by microprobe analysis.) This phase has the concentrations C _Alp, C_yp, and C_zp of Al and elements y and z. Assume that the sensitivity factor S_y/Al has been determined, and that the sensitivity factor S_z/Al is to be determined. When the material is sputtered, a cylindrical area with a diameter of 30 μm is continuously analysed. Assume that the intensities of the elements are I_y1 and I_z1 when only matrix is analysed, and I_y2 and I_z2 when analysed area consists of matrix and a fraction F_p of particles. Since the sensitivity factor S_Y/Al of the element y has been determined previously, the concentrations C_y1 and C_y2 of element y in the two analysed volumes can be calculated using Eqs. (1). The latter concentration is given by:

(A1) C y 2 = C y 1 1 − F p + C y p F p

The volume fraction of particles of the intermetallic phase X is determined by rearranging of Eq. (A1):

(A2) F p = C y 2 − C y 1 C y p − C y 1

The intensity of element z in the volume containing the particle is:

(A3) I z 2 = I z 1 1 − F p + I z p F p

where I_zp is the intensity of element z if the analysed volume contained the intermetallic phase X only_. The intensity I_zp can be calculated from Eq. (A3). Finally, the sensitivity factor of element z is according to Eq. (1b):

(A4) S z / A l = I z 2 ⋅ f A l ⋅ C A l I A l ⋅ f z ⋅ C z 2 = I z 1 ⋅ f A l ⋅ C A l I A l ⋅ f z ⋅ C z 1

(A5) I z 1 C z 1 = I z 2 C z 2

The concentration of element z in the area (volume) containing the particles is:

(A6) C z 2 = C z 1 1 − F p + C z p F p

The concentration C_z2 can be calculated from Eqs. (A5) and (A6):

(A7) C z 2 = F p ⋅ C z p I z 2 − I z 1 1 − F p

By means of Eq. (A7), the sensitivity factor of element z can be calculated:

(A8) S z / A l = I z 2 ⋅ f A l ⋅ C A l ⋅ I z 2 − I z 1 1 − F p I A l ⋅ f z ⋅ C z p ⋅ F p

Received: 2001-11-02

Published Online: 2022-01-04

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Articles in the same Issue

https://doi.org/10.3139/ijmr-2002-0059

Keywords for this article

Aluminium alloys; SIMS; Solid solution; Microstructure