Aluminum alloy is widely used in various industries and is a new type of structural and functional material. Compared with traditional structural materials, aluminum alloy materials have advantages of high strength, light weight, strong corrosion resistance, less pollution and low cost. Different special metal elements are added to aluminum alloys to improve the performance of the alloy, which can be adapted to different needs, but the impurity elements must be controlled simultaneously to improve the quality of the alloy. Aluminum alloys have different properties depending on the composition of their alloying elements. Therefore, aluminum alloy is widely used in automobile, aviation, machinery manufacturing, rail transportation and other industries.

The traditional methods for analyzing the content of each element in aluminum alloy are spectrophotometry, atomic absorption spectrometry and photoelectric direct reading spectrometry. The first two methods can analyze a single element, and the operation is complicated, time-consuming and laborious, and the efficiency is low; photoelectric direct reading spectrometry can analyze multiple elements at the same time, and the operation is easy, but it can only analyze block samples. ICP-OES has the advantages of high sensitivity, fast analysis speed, small matrix effect, wide linear range, simultaneous analysis of multiple elements, no specific requirements for sample shape, etc. It is widely used in metallurgical, chemical and geological industries.

The test referred Chinese National Standard “GB/T 20975.25-2020 Methods for chemical analysis of aluminium and aluminium alloys—Part 25：Determination of elements content—Inductively coupled plasma atomic emission spectrometric method” to verify the inorganic elements in aluminum alloy by inductively coupled plasma emission spectrometer for Mn, Mg, Cr, Fe, Ti, V, Zn, Cu and Ni.

Table 1: Testing Data of EXPEC-6000R Type ICP-OES

Reagent and standard solution

High purity aluminum: purity > 99.999%
Nitric acid: ρ(HNO3) = 1.42 g/mL, superior purity
Hydrochloric acid: ρ(HCl) = 1.19 g/mL, superior purity
Ultrapure water: resistivity ≥ 18.2 MΩ-cm (25℃), the rest of indicators meet the first grade standard in GB/T 6682.
Standard solution: Cr, Fe, Ti, V, Zn, Cu, Mn, Mg, Ni single element standard solution 1000mg/L (National Center for Analysis and Testing of Non-ferrous Metals and Electronic Materials)
Argon: High purity argon, purity 99.999%
Pure water: 18.2MΩ deionized water

Sample pre-treatment
Self-purchased standard alloy ZBY5211 with certificate value was used as the sample for the experiment. Weigh the sample and add a certain amount of aqua regia until the sample is completely dissolved. Cool to room temperature and precise the volume adjustment.

Standard curve and detection limit
The standard curve was plotted by selecting the appropriate spectral lines for the elements under test, and the linearity coefficient R>0.9995 was found to be good. The standard curve was plotted using the lowest dilution and the sample blank was measured 11 times consecutively to calculate the method detection limits for each element. The linearity coefficients and method detection limits were listed in below table.

Table 2: Measured elements, correlation coefficient and detection limit

Table 3: Sample precision

Table 4: Element detemination results of aluminum alloy

Conclusion
The above experimental results show that the determination of the elemental content in aluminum alloy samples by inductively coupled plasma emission spectrometry is of great significance for the study of the properties of aluminum alloy materials. The results showed that the method detection limits of the elements to be measured were 0.00002~0.00064%, the spiked recoveries were between 98.2% and 102.4%, and the absolute errors of the determination met the reproducibility limits of the national standard GB/T 20975.25-202. The method is rapid, with high data reliability, and can be widely used in the detection of aluminum alloy content.

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