1、Designation: E 1251 07Standard Test Method forAnalysis of Aluminum and Aluminum Alloys by AtomicEmission Spectrometry1This standard is issued under the fixed designation E 1251; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method describes th
3、e analysis of aluminum andits alloys by atomic emission spectrometry. The aluminumspecimen to be analyzed may be in the form of a chill cast disk,casting, foil, sheet, plate, extrusion or some other wrought formor shape. The elements covered in the scope of this method arelisted in the table below.E
4、lementTested Concentration Range(Wt %)Beryllium 0.0004 to 0.24Bismuth 0.03 to 0.6Boron 0.0006 to 0.009Calcium 0.0002 to Chromium 0.001 to 0.23Cobalt 0.4 to Copper 0.001 to 5.5Gallium 0.02 to Iron 0.2 to 0.5Lead 0.04 to 0.6Lithium 0.0003 to 2.1Magnesium 0.03 to 5.4Manganese 0.001 to 1.2Nickel 0.005 t
5、o 2.6Phosphorus 0.003 to Silicon 0.07 to 16Sodium 0.003 to 0.02Strontium 0.03 to Tin 0.03toTitanium 0.001 to 0.12Vanadium 0.002 to 0.022Zinc 0.002 to 5.7Zirconium 0.001 to 0.12NOTE 1The concentration ranges given in the above scope wereestablished through cooperative testing (ILS) of selected refere
6、nce mate-rials. The range shown for each element does not demonstrate the actualusable analytical range for that element. The usable analytical range maybe extended higher or lower based on individual instrument capability,spectral characteristics of the specific element wavelength being used andthe
7、 availability of appropriate reference materials.1.2 This test method is suitable primarily for the analysis ofchill cast disks as defined in Practices E 716. Other forms maybe analyzed, provided that: (1) they are sufficiently massive toprevent undue heating, (2) they allow machining to provide acl
8、ean, flat surface, which creates a seal between the specimenand the spark stand, and (3) reference materials of a similarmetallurgical condition and chemical composition are avail-able.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is the
9、responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific safety andhealth statements are given in Section 10.2. Referenced Documents2.1 ASTM Standards:2E 135 Terminology Relatin
10、g to Analytical Chemistry forMetals, Ores, and Related MaterialsE 158 Practice for Fundamental Calculations to ConvertIntensities into Concentrations in Optical Emission Spec-trochemical Analysis3E 172 Practice for Describing and Specifying the ExcitationSource in Emission Spectrochemical Analysis3E
11、 305 Practice for Establishing and Controlling AtomicEmission Spectrochemical Analytical CurvesE 406 Practice for Using Controlled Atmospheres in Spec-trochemical AnalysisE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 716 Practices for Sampling Alu
12、minum and AluminumAlloys for Spectrochemical AnalysisE 826 Practice for Testing Homogeneity of Materials forDevelopment of Reference Materials3E 876 Practice for Use of Statistics in the Evaluation ofSpectrometric Data3E 1329 Practice for Verification and Use of Control Charts1This test method is un
13、der the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores and Related Materials and is the directresponsibility of Subcommittee E01.04 on Aluminum and Magnesium.Current edition approved June 1, 2007. Published June 2007. Originallyapproved in 1988. Last previous edition appr
14、oved in 2004 as E 1251 04.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM Internat
15、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.in Spectrochemical AnalysisE 1507 Guide for Describing and Specifying the Spectrom-eter of an Optical Emission Direct-Reading Instrument3. Terminology3.1 DefinitionsFor definitions of terms used in this Stan-d
16、ard, refer to Terminology E 135.3.2 Definitions of Terms Specific to This Standard:3.2.1 binary type calibrationcalibration curves deter-mined using binary calibrants (primary aluminum to which hasbeen added one specific element).3.2.2 global type calibrationcalibration curves deter-mined using cali
17、brants from many different alloys with con-siderable compositional differences.3.2.3 alloy type calibrationcalibration curves determinedusing calibrants from alloys with similar compositions.3.2.4 two point drift correctionthe practice of analyzing ahigh and low standardant for each calibration curv
18、e andadjusting the counts or voltage values obtained back to thevalues obtained on those particular standardants during thecollection of the calibration data. The corrections are accom-plished mathematically and are applied to both the slope andintercept. Improved precision may be obtained by using
19、amulti-point drift correction as described in Practice E 1329.3.2.5 type standardizationmathematical adjustment of thecalibration curves slope or intercept using a single standardant(reference material) at or close to the nominal composition forthe particular alloy being analyzed. For best results t
20、hestandardant being used should be within 610 % of the com-position (for each respective element) of the material beinganalyzed.4. Summary of Test Method4.1 A unipolar triggered capacitor discharge is produced inan argon atmosphere between the prepared flat surface of aspecimen and the tip of a semi
21、-permanent counter electrode.The energy of the discharge is sufficient to ablate material fromthe surface of the sample, break the chemical or physicalbonds, and cause the resulting atoms or ions to emit radiantenergy. The radiant energies of the selected analytical lines andthe internal standard li
22、ne(s) are converted into electrical signalsby either photomultiplier tubes (PMTs) or a suitable solid statedetector. The detector signals are electrically integrated andconverted to a digitized value. The signals are ratioed to theproper internal standard signal and converted into concentra-tions by
23、 a computer in accordance with Practice E 158.4.2 Three different methods of calibration defined in 3.2.1,3.2.2 and 3.2.3, are capable of giving the same precision,accuracy and detection limit.4.2.1 The first method, binary calibration, employs calibra-tion curves that are determined using a large n
24、umber ofhigh-purity binary calibrants. This approach is used when thereis a need to analyze almost the entire range of aluminum alloys.Because binary calibrants may respond differently from alloycalibrants, the latter are used to improve accuracy by applyinga slope and/or intercept correction to the
25、 observed readings.4.2.2 The second method, global calibration, employs cali-bration curves that are determined using many different alloycalibrants with a wide variety of compositions. Mathematicalcalculations are used to correct for both alloy difference andinter-element effects. Like the method a
26、bove, specific alloycalibrants may be used to apply a slope and/or interceptcorrection to the observed readings.4.2.3 The third method, alloy calibration, employs calibra-tion curves that are determined using different alloy calibrantsthat have similar compositions. Again, specific alloy calibrantsm
27、ay be used to apply a slope and/or intercept correction to theobserved readings.5. Significance and Use5.1 The metallurgical properties of aluminum and its alloysare highly dependant on chemical composition. Precise andaccurate analyses are essential to obtaining desired properties,meeting customer
28、specifications and helping to reduce scrapdue to off-grade material.5.2 This test method is applicable to chill cast specimens asdefined in Practice E 716 and can also be applied to other typesof samples provided that suitable reference materials areavailable. Also, other sample forms can be melted-
29、down andcast into a disk, using an appropriate mold, as described inPractice E 716. However, it should be noted that some ele-ments (for example, magnesium) readily form oxides, whilesome others (for example, sodium, lithium, calcium, andstrontium) are volatile, and may be lost to varying degreesdur
30、ing the melting process.6. Recommended Analytical Lines and PotentialInterferences6.1 Table 1 lists the analytical lines commonly used foraluminum analysis. Other lines may be used if they givecomparable results.Also listed are recommended concentrationrange, background equivalent concentration (BEC
31、), detectionlimit, useful linear range, and potential interferences. Thevalues given in this table are typical; actual values obtained aredependent on instrument design.NOTE 2The BEC and detection limits listed in Table 1 have beenattained with a spectrometer that has a reciprocal dispersion of 54 n
32、m/mmand a working resolution of 3.5 nm, using an entrance slit width of 25 mand exit slit widths of 50 m.7. Apparatus7.1 Specimen Preparation Equipment:7.1.1 Sampling Molds, for aluminum and the techniques ofpouring a sample disk are described in Practice E 716. Chillcast samples, poured and cast as
33、 described within PracticeE 716 shall be the recommended form in this test method.7.1.2 Lathe, capable of machining a smooth, flat surface onthe reference materials and samples. A variable speed cutter, acemented carbide or polycrystalline diamond tool bit, and anautomatic cross-feed are highly reco
34、mmended. Proper depth ofcut and desired surface finish are described in Practice E 716.7.1.3 Milling Machine, a milling machine can be used as analternative to a lathe.7.2 Excitation Source, capable of producing a unipolar,triggered capacitor discharge. In todays instrumentation, theexcitation sourc
35、e is computer controlled and is normallyprogrammed to produce: (1) a high-energy pre-spark (of somepreset duration), (2) a spark-type discharge (of some presetE1251072TABLE 1 Recommended Analytical LinesElementWavelengthin Air(nm)ARecommendedConcentrationRange, %BackgroundEquivalent,%BCalculatedDete
36、ctionLimit, %C,DHighConcentrationIndex, %EInterferencesElement, l(nm) and k, %FAluminum I 256.799 70-100I 266.039 70-100I 237.208 70-100Antimony I 231.147 0.001-0.5 0.17 0.0002 Co 231.166 0.6I 259.806 0.001-0.5 0.0002 Fe 259.837Mn 259.817 0.01Arsenic 234.984 0.005-0.1Beryllium I 234.861 0.0001-0.05
37、0.001 0.00003II 313.042 0.0001-0.05 0.0035 0.00001332.134 0.0001-0.05 0.00001Bismuth I 306.772 0.001-0.7 0.04 0.0002Boron I 249.773 0.0001-0.05 0.002 0.0001* Fe 249.782 0.001Mn 249.778 0.007I 249.678 0.0001-0.05I 208.959 0.0001-0.05 Mo 208.952 0.13Cadmium I 228.802 0.001-1 0.05 20 Fe 296.128II 224.7
38、00 0.01-5 0.03 0.0005* 5I 510.554 0.05-20 0.32 0.01* 20Gallium I 294.364 0.001-0.05 0.015 11I 383.231G0.01-11 0.015 0.002* 11I 383.826 0.1-11I 518.362 0.01-11 0.02 0.002* 11Manganese I 403.076G0.001-0.1 0.028 0.0001*II 259.373II 293.3060.0005-0.50.001-20.0040.0060.000050.0002*0.21.1II 346.033B 0.01-
39、2Nickel I 341.476 0.001-2 0.02 2.5 Zr 341.466 0.01I 310.188 0.005-4 0.05 0.001* 5II 231.604 0.001-2 0.015 0.0005* 24 Cr 390.566 0.09I 212.415 0.05-24 0.5 0.05 24Silver I 328.068 0.0005-0.1I 338.289 0.0001-0.1 10I 466.848 0.05-1.5Sodium I 588.995 0.0001-0.05 0.0015 10Titanium II 334.904 0.0005-0.5 0.
40、004 8I 481.053 0.01-10 0.07 0.001* 10I 472.216 0.01-10 0.26 0.0015 10Zirconium II 339.198 0.001-1 0.02 0.001*II 349.621G0.001-1 0.006 0.0001AI = atom line, II = ion line. Second (2nd) indicates that the second order shall be used, where available.BBackground Equivalent Concentration (BEC)The concent
41、ration at which the signal due to the element is equal to the signal due to the background.CIn this test method, the calculated detection limit was measured by calculating the standard deviation of ten consecutive burns on a specimen with elementconcentration(s) at levels below ten times the expecte
42、d detection limit.DSee footnote C. For values marked with an asterisk (*) the available data was for a concentration greater than ten (10) times but less than a hundred (100) times theexpected detection limit.EHigh Concentration IndexThe concentration at which the slope of the calibration curve drop
43、s below 0.75.FInterference Factor, kThe apparent increase in the concentration of the element being determined, expressed in percent, due to the presence of 1.0 % of theinterfering element.GUseful analytical lines with improved signal to background ratios due to the complete removal of C-N backgroun
44、d by the argon atmosphere.HIf phosphorus is to be determined, the most sensitive line appears to be the 178.231 nm in the second order which requires either a vacuum or a gas filled spectrometer.The vacuum spectrometer should be operated at a pressure of 25 microtorr or less. The gas filled spectrom
45、eter will be charged with nitrogen to a positive pressure of slightlyover one atmosphere (101 k pa). Optimum results are obtained by using a background channel that has been profiled “off peak” of the first order 178.231 nm phosphorusline as the internal standard. The ratio of P 178.231 nm (2nd) / b
46、ackground near the 178.231 nm (1st) is plotted against % phosphorus. Even with this compensation forvariability in background, alloys with highly different compositions of major alloying elements, particularly silicon, require separate reference materials and analytical curves.TABLE 2 Typical Excita
47、tion Source Electrical ParametersParameterHigh EnergyPre-sparkSpark ArcResistance, V 1115Inductance, H 30 130 30Volts, V 400 400 400Frequency, Hz 300 300 300Capacitance, F 12 3 5Time, s 10 5 5E12510742 ppm of oxygen or a few ppm of water vapor.7.5 SpectrometerFor details on specifying the spectrom-e
48、ter please refer to Guide E 1507.7.6 Measuring and Control System of the instrument con-sists of either photomultiplier and integrating electronics orsolid-state photosensitive arrays (CCD or CID) that convertobserved light intensities to a digitizable signal. A dedicatedcomputer and/or microprocess
49、or is used to control burn con-ditions, source operation, data acquisition and the conversionof intensity data to concentrations. Data should be accessible tothe operator throughout all steps of the calculation process.Concentration data may be automatically transferred to a sitemainframe computer or server for further data storage anddistribution. The instruments control software should includefunctions for routine instrument drift correction (standardiza-tion), type standardization and the application of these func-tions to subsequent analyses.8. Materials8
