Iron-nickel-based superalloy is a superalloy material based on iron-nickel. It not only has good high-temperature oxidation resistance and corrosion resistance, but also has excellent high-temperature strength, material durability strength, and good fatigue resistance. Secondly, iron-nickel-based superalloys have high tensile strength and good ductility at room temperature, and this trend can be maintained up to 850 °C. However, the existence of trace elements in metals and alloys has a negative impact on material properties. In the process of alloy smelting and use, strict control of its content is required.
Due to the complex composition of the iron-nickel-based superalloy, the interference of the matrix on the measurement results is very serious, which makes it difficult to accurately determine the trace elements in the sample. The He gas collision mode of the single quadrupole mass spectrometer cannot eliminate the complex matrix interference of the iron-nickel alloy, which makes the test results seriously large and cannot meet the detection requirements. Based on this situation, the triple quadrupole (ICP-MS/MS) utilizes the superior reaction cell technology, based on the oxygen in situ mass mode, to make the interfering ions react with oxygen, so as to realize the effective separation of the interfering ions and the element ions to be analyzed. Realize the stable test and analysis of Cd content in complex iron-nickel matrix. For other elements with less interference, based on the powerful collision cell technology of the triple quadrupole, good test and analysis of this series of elements can be achieved.
The application center uses ICP-MS/MS to directly inject samples after acid dissolution of iron-nickel-based alloy samples, and uses oxygen in situ mass mode to test Cd in iron-nickel-based alloys, and collision mode to test Mg, Ca, As, Ga, In , Zn, Sb, Se, Tl, Pb, Te, Sn, Ag, Bi, the two modes are combined to realize the determination of the content of various elements in iron-nickel-based alloys, and complete the stability test analysis of trace elements in iron-nickel-based alloy samples .
Experimental part
Instrument
Table 2 Detection parameters of inductively coupled plasma mass spectrometer
Reagents and Standards
- Reagents superior pure nitric acid, superior pure hydrochloric acid, superior pure hydrofluoric acid; Remarks: higher purity reagents can be purchased (G3 grade)
- Pure water 18.25 MΩ·cm deionized water (25°C)
- Standard solution Mg, Ca, As, Ga, In, Zn, Sb, Se, Tl, Pb, Te, Sn, Cd, Ag, Bi single element standard solution, 1000 μg/mL, (National Institute of Nonferrous Metals).
Sample handling
Weigh 0.1 g of sample into PFA Beaker ➡ Add nitric acid, hydrochloric acid, hydrofluoric acid in sequence ➡ Heat on a 130°C electric hot plate ➡ Digest completely, after cooling, transfer ultrapure water to 100 mL PP bottle to constant volume
Detection limit
The blank sample was analyzed continuously for 11 times with the whole process method, and the obtained results were calculated by the dilution factor of 3 times the standard deviation to calculate the method detection limit of each element, as shown in Table 2. The measured mass numbers, analysis modes, and linear correlations (correlation coefficients measured by R2) of each element are also listed in Table 3.
Table 3 Mass numbers, correlation coefficients and detection limits of the determined elements
Test precision
In order to examine the stability of the instrument when measuring samples, continuous sample injection and analysis were performed 10 times to test the precision of the system. The RSD values of the measured values of all elements were lower than 5.67%.
Table 4 Sample precision (n=10)
Actual sample test
Table 5 Test results of element content in iron-nickel-based superalloys (mg/kg)
Conclusion
In this paper, the iron-nickel-based alloy is directly injected into the sample after digestion with mixed acid, and the triple quadrupole oxygen in situ mass mode is used to test the Cd in the iron-nickel-based alloy, and the collision mode is used to test Mg, Ca, As, Ga, In, Zn, Sb , Se, Tl, Pb, Te, Sn, Ag, Bi, the two modes are combined to realize the determination of the content of various elements in iron-nickel-based alloys. Through the test and analysis of the iron-nickel-based standard substance GBW-01620, the results show that the test values of the 15 elements are all within the uncertainty range of the certified value, and the data accuracy is basically consistent with the reference value. The method can realize the stable test and analysis of Ag, Bi, Ca, In, Mg, Sb, Se, Pb, As, Tl, Sn and other contents in iron-nickel-based alloy samples.
