138 Prakt. Met. Sonderband 46 (2014) 
Goransson et al. were among the first to show that using the information from single spark 
intensity diagrams it is possible to analyze micro-inclusion size distribution, composition 
and others within 10 minutes after collecting the sample [3]. The principles and the 
phenomenology of the inclusion analysis technique using single spark intensity information 
were described in several articles [3, 4, 5]. 
2. PRINCIPLES OF SPARK-DAT METHODS 
In spark-OES spectrometry, typical acquisition involves few thousands high-frequency Fig. 2: 
single sparks, applied between the sample and the electrode, in order to ablate and excite Coincid 
the material. With Spark-DAT the single intensity values corresponding to the single 
sparks are acquired separately and processed with fast specialized on-line algorithms. 
The intensity of a Spark-DAT signal depends on the composition of the sample at the 3. PHEN! 
position struck by the corresponding single spark. If the concentration of an element in the 
ablated sample material is significantly higher than the concentration of its soluble form in The effect 
the matrix, the outcome is an intensity peak. In steel, this is typically the case when a observed 1 
single spark hits a sample area containing an Al based inclusion (Fig. 1). spread frol 
ALO spark m volume ablated traces. Th 
inclusion by single spark m intensity metal matr 
on Al craters are 
nt sample spark is the 
= number 
if atoms 
spars n ! x 
’ spam wuson "1 Le | | outer 
in . | inclusion o 
re inclusion 
CL 
« number Al 
atoms in 
matrix 
+ 
spark Fig. 3: 
number milled 
- ablating 
6 um, r 
surface 
Fig. 1. Principle of Spark-DAT illustrated with a steel sample containing Al2O3 
inclusions. Sparks m, n and o strike inclusions which give rise to peaks having When seve 
intensity in proportion to the volume of the inclusion. formed, ar 
Suitable ba 
correspong 
The intensity of the baseline intensity is proportional to the concentration of Al atoms wo to five 
dissolved in the matrix and the intensity of a peak depends on the amount of Al atoms progresses 
contained in the inclusion(s) ablated by a single spark. Consequently, the number of peaks 
is in proportion to the number of such inclusions and their intensity to such factors as the 4. QUAL. 
volume of the inclusion and the concentration of Al in the inclusion. 
Coincidental intensity peaks, i.e. peaks corresponding to the same single spark and arising Basic Spar 
on two element channels indicate with high likelihood the presence of the two elements in a simple a 
the same inclusion (Fig. 2). this eleme: 
1 
mars