1、Designation: B 954 07Standard Test Method forAnalysis of Magnesium and Magnesium Alloys by AtomicEmission Spectrometry1This standard is issued under the fixed designation B 954; 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.1. Scope1.1 This test method describes the analysis of magnesiumand its alloys by atomic emission spectrometry. The magne-
3、sium specimen to be analyzed may be in the form of a chill castdisk, casting, sheet, plate, extrusion or some other wroughtform or shape. The elements covered in the scope of thismethod are listed in the table below.Element Concentration Range (Wt %)Aluminum 0.001 to 12.0Beryllium 0.0001 to 0.01Boro
4、n 0.0001 to 0.01Cadmium 0.0001 to 0.05Calcium 0.0005 to 0.05Cerium 0.01 to 3.0Chromium 0.0002 to 0.005Copper 0.001 to 0.05Dysprosium 0.01 to 1.0Erbium 0.01 to 1.0Gadolinium 0.01 to 3.0Iron 0.001 to 0.06Lanthanum 0.01 to 1.5Lead 0.005 to 0.1Lithium 0.001 to 0.05Manganese 0.001 to 2.0Neodymium 0.01 to
5、 3.0Nickel 0.0005 to 0.05Phosphorus 0.0002 to 0.01Praseodymium 0.01 to 0.5Samarium 0.01 to 1.0Silicon 0.002 to 5.0Silver 0.001 to 0.2Sodium 0.0005 to 0.01Strontium 0.01 to 4.0Tin 0.002 to 0.05Titanium 0.001 to 0.02Yttrium 0.02 to 7.0Ytterbium 0.01 to 1.0Zinc 0.001 to 10.0Zirconium 0.001 to 1.0NOTE 1
6、The concentration ranges given in the above scope areestimates based on two manufacturers observations and data provided bya supplier of atomic emission spectrometers. The range shown for eachelement does not demonstrate the actual usable analytical range for thatelement. The usable analytical range
7、 may be extended higher or lowerbased on individual instrument capability, spectral characteristics of thespecific element wavelength being used and the availability of appropriatereference materials.1.2 This test method is suitable primarily for the analysis ofchill cast disks as defined in Samplin
8、g Practice B 953. Otherforms may be analyzed, provided that: (1) they are sufficientlymassive to prevent undue heating, (2) they allow machining toprovide a clean, flat surface which creates a seal between thespecimen and the spark stand, and (3) reference materials of asimilar metallurgical conditi
9、on (spectrochemical response) andchemical composition are available.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the a
10、pplica-bility of regulatory limitations prior to use. Specific safety andhealth statements are given in Section 10.2. Referenced Documents2.1 ASTM Standards:2B 953 Practice for Sampling Magnesium and MagnesiumAlloys for Spectrochemical AnalysisE 135 Terminology Relating to Analytical Chemistry forMe
11、tals, 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 305 Practice for Establishing
12、and Controlling Spectro-chemical Analytical Curves3E 406 Practice for Using Controlled Atmospheres in Spec-trochemical AnalysisE 826 Practice for Testing Homogeneity of Materials forDevelopment of Reference Materials3E 876 Practice for Use of Statistics in the Evaluation ofSpectrometric Data3E 1257
13、Guide for Evaluating Grinding Materials Used forSurface Preparation in Spectrochemical AnalysisE 1329 Practice for Verification and Use of Control Charts1This test method is under the jurisdiction of ASTM Committee B07 on LightMetals and Alloys and is the direct responsibility of Subcommittee B07.04
14、 onMagnesium Alloy Cast and Wrought Products.Current edition approved June 1, 2007. Published June 2007.2For 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 standard
15、s Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 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 Instr
16、ument3. Terminology3.1 DefinitionsFor definitions of terms used in this stan-dard, 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 magnesium to whichhas been added one specific
17、element).3.2.2 global type calibrationcalibration curves deter-mined using calibrants 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 correcti
18、onthe practice of analyzing ahigh and low standardant for each calibration curve 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 appli
19、ed to both the slope andintercept. Improved precision may be obtained by using 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
20、 nominal composition forthe particular alloy being analyzed. For best results thestandardant 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
21、atmosphere between the prepared flat surface of aspecimen and the tip of a semi-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. Th
22、e radiant energies of the selected analytical lines andthe internal standard line(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 rati
23、oed to theproper internal standard signal and converted into concentra-tions by 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 equivalent precision,accuracy and detection limits.4.2.1 The first method, b
24、inary calibration, employs calibra-tion curves that are determined using a large number ofhigh-purity binary calibrants. This approach is used when thereis a need to analyze almost the entire range of magnesiumalloys. Because binary calibrants may respond differently fromalloy calibrants, the latter
25、 are used to improve accuracy byapplying a slope and/or intercept correction to the observedreadings.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 use
26、d to correct for both alloy difference andinter-element effects. Like the method above, 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 various a
27、lloy calibrantsthat have similar matrix compositions. Again, specific alloycalibrants may be used to apply a slope and/or interceptcorrection to the observed readings.5. Significance and Use5.1 The metallurgical properties of magnesium and itsalloys are highly dependant on chemical composition. Prec
28、iseand accurate analyses are essential to obtaining desired prop-erties, meeting customer specifications and helping to reducescrap due to off-grade material.5.2 This test method is applicable to chill cast specimens asdefined in Practice B 953 and can also be applied to other typesof samples provid
29、ed that suitable reference materials areavailable.6. Interferences6.1 Table 1 lists analytical lines commonly used for mag-nesium analysis. Other lines may be used if they give compa-rable results.Also listed are recommended concentration range,background equivalent concentration (BEC), detection li
30、mits,and potential interferences where available. The values givenin this table are typical; actual values obtained are dependenton instrument design and set-up.7. Apparatus7.1 Specimen Preparation Equipment:7.1.1 Sampling Molds, for magnesium the techniques ofpouring a sample disk are described in
31、Practice B 953. Chillcast samples, poured and cast as described within PracticeB 953 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. Either alloy steel, carbide-tipped, or carbide insert tool bits are r
32、ecommended. Properdepth of cut and desired surface finish are described in PracticeB 953.7.1.3 Milling MachineA milling machine can be used asan alternative to a lathe.7.1.4 Metallographic Polisher/GrinderA metallographicpolisher/grinder may also be used to prepare the sample surfaceprovided care ha
33、s been taken in the selection a non-contaminating abrasive compound. Metallographic grade wet/dry silicon carbide discs of 120 grit or higher will produce agood sample surface with essentially no silicon carryover to thesample. This must be verified by making a comparisonbetween freshly prepared sur
34、faces on a polisher/grinder to thatof a lathe or milling machine. Reference Guide E 1257 for adescription of contamination issues with various abrasivecompounds.7.2 Excitation Source, capable of producing a unipolartriggered capacitor discharge. In todays instrumentation theexcitation source is comp
35、uter controlled and is normallyB954072TABLE 1 Recommended Analytical LinesElementWavelength in Air(nm)ARecommendedConcentrationRange, %BackgroundEquivalent,%BDetectionLimit,%CInterferences Element,l(nm)Aluminum 396.15 I 0.001 0.5 0.008 0.0001* Zr 396.16Aluminum 256.80 I 1.0 12.0 ZnAr256.81256.81Alum
36、inum 266.04 I 1.0 12.0Aluminum 394.40 I 0.001 0.5 0.002Aluminum 308.22 I 1.0 12.0 0.09 Mn 308.21Beryllium 313.04 II 0.0001 0.01 0.0005 0.0001 AgCe313.00313.09Boron 182.64 I CoMg182.60182.68Boron 249.68 I FeFeAlCe249.65249.70249.71249.75Cadmium 226.50 II 0.0001 0.05 0.002 0.00005 CeNiFe226.49226.4522
37、6.44Cadmium 228.80 I 0.00003 0.1 CeNiFe228.78228.77228.73Calcium 393.37 II 0.0005 0.05 0.0002 0.0002 FeCeZr393.36393.37393.41Cerium 413.77 II 0.01 3.0 ZrFe413.74413.78Cerium 418.66 II 0.01 3.0 Dy 418.68Chromium 425.44 I 0.0002 0.005 CeCu425.34425.56Copper 324.75 I 0.001 0.05 0.003 0.0001 MnMn324.753
38、24.85Dysprosium 353.17 II 0.01 1.0 MnMn353.19353.21Erbium 400.80 II 0.01 1.0 0.08 0.001 MnSm400.80400.81Gadolinium 379.64 0.01 3.0 0.1 0.001 Zr 379.65Iron 259.94 II 0.001 0.06 0.023 0.0005 Mn 259.89Iron 238.20 II ZnCeZr238.22238.23238.27Iron 371.99 I 0.001 0.06 0.007 Ti 372.04Lanthanum 433.37 II 0.0
39、1 1.5 0.1 0.001 PrSm433.39433.41Lead 368.35 I 0.005 0.1 FeMnZn368.31368.35368.35Lead 363.96 I 0.05 0.5 ZnFe363.95364.04Lead 217.00 I 0.005 0.1 0.04 MnCe216.98216.95Lithium 670.78 I 0.001 0.05Lithium 610.36 IMagnesium 291.55 I Internal Standard MnAl291.46291.57Magnesium 517.27 I Internal Standard Fe
40、517.16Manganese 257.61 II 0.001 0.5 MnFe257.57257.69Manganese 259.37 II 0.002 0.5 MgZrFe259.32259.37259.37Manganese 293.31 II 0.001 2 0.12Manganese 403.08 I 0.001 0.5 0.006 0.0002 ZrFe403.07403.05Manganese 403.45 I 0.01 0.5Neodymium 406.11 II 0.01 3.0 Mn 406.17Nickel 231.60 II 0.001 0.05Nickel 351.5
41、1 I 0.001 0.05 Zn 351.51Nickel 341.48 I 0.0005 0.05 0.015 0.0003 Zr 341.47Phosphorous 178.28 I 0.0002 0.01 0.009 0.0001 Zr 178.33Praseodymium 422.30 0.01 0.5 0.1 0.001Samarium 356.83 II 0.01 1.0 0.1 0.001 Fe 356.84B954073programmed to produce: (1) a high-energy pre-burn (of somepreset duration), and
42、 (2) an arc/spark-type discharge (of somepreset duration) for the exposure burn during which time theanalytical data is gathered and processed by the system.7.2.1 Typical parameters and exposure times are given inTable 2. It should be emphasized that the information presentedis given as an example o
43、nly and parameters may vary withrespect to instrument model and manufacturer. For details ondescribing and specifying an excitation source, please refer toPractice E 172.7.3 Excitation Chamber shall be designed with an upperplate that is smooth and flat so that it will mate (seal) perfectlywith the
44、prepared surface of the sample specimen. The seal thatis formed between the two will exclude atmospheric oxygenfrom entering the discharge chamber. The excitation chamberwill contain a mounting clamp to hold the counter electrode.The excitation stand assembly will also have some type ofclamp or devi
45、ce designed to hold the sample firmly against thetop plate. Some manufacturers may provide for the top plate tobe liquid cooled to minimize sample heat-up during theexcitation cycle. The excitation chamber will also be con-structed so that it is flushed automatically with argon gasduring the analyti
46、cal burn cycle. The excitation chambersdesign should allow for a flow of argon gas to prevent thedeposition of ablated metal dust on the inner-chamber quartzwindow(s). The excitation chamber will be equipped with anexhaust system that will safely dispose of the argon gas and themetal dust created du
47、ring the excitation cycle. For reasons ofhealth and cleanliness, the exhausted gas and dust should notbe vented directly into the laboratory. To help with thissituation, manufacturers have designed their instruments withsome type of exhaust/filter system to deal with this problem.The exhaust can the
48、n be vented into an efficient hood system.7.4 Gas Flow System will be designed so that it can deliverpure argon gas to the excitation chamber. The purity of theargon gas will affect the precision of the results. Generally,precision improves as the purity of the argon gas gets higher.Argon gas with a
49、 minimum purity of 99.995 % has been foundto be acceptable. The gas shall be delivered by a flow systemas described in Practice E 406. The argon gas source can befrom high-purity compressed gas cylinders, a cryogenic-typeTABLE 1 ContinuedElementWavelength in Air(nm)ARecommendedConcentrationRange, %BackgroundEquivalent,%BDetectionLimit,%CInterferences Element,l(nm)Silicon 251.61 I 0.002 1.5 0.013 ZnVAl251.58251.61251.59Silicon 288.16 I 0.002 1.5 0.088 0.0006 Al 288.15Silicon 390.55 I 0.5 5 1.0? Mn 39
