1、Designation: B954 07B954 15Standard Test Method forAnalysis of Magnesium and Magnesium Alloys by AtomicEmission Spectrometry1This standard is issued under the fixed designation B954; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the analysis of magnesium and its alloys by atomic emission spectrometry. The m
3、agnesiumspecimen to be analyzed may be in the form of a chill cast disk, casting, sheet, plate, extrusion or some other wrought form orshape. The elements covered in the scope of this method are listed in the table below.Element Concentration Range (Wt %)Element Mass Fraction Range (Wt %)Aluminum 0.
4、001 to 12.0Beryllium 0.0001 to 0.01Boron 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 0.05
5、Manganese 0.001 to 2.0Neodymium 0.01 to 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.
6、001 to 10.0Zirconium 0.001 to 1.0NOTE 1The concentration mass fraction ranges given in the above scope are estimates based on two manufacturers observations and data providedby a supplier of atomic emission spectrometers. The range shown for each element does not demonstrate the actual usable analyt
7、ical range for thatelement. The usable analytical range may be extended higher or lower based on individual instrument capability, spectral characteristics of the specificelement wavelength being used and the availability of appropriate reference materials.1.2 This test method is suitable primarily
8、for the analysis of chill cast disks as defineddescribed in Sampling Practice B953.Other forms may be analyzed, provided that: (1) they are sufficiently massive to prevent undue heating, (2) they allow machiningto provide a clean, flat surface which creates a seal between the specimen and the spark
9、stand, and (3) reference materials of asimilar metallurgical condition (spectrochemical response) and chemical composition are available.1 This test method is under the jurisdiction of ASTM Committee B07 on Light Metals and Alloys and is the direct responsibility of Subcommittee B07.04 on MagnesiumA
10、lloy Cast and Wrought Products.Current edition approved June 1, 2007Oct. 1, 2015. Published June 2007November 2015. Originally approved in 2007. Last previous edition approved in 2007 asB954 07. DOI: 10.1520/B0954-07.10.1520/B0954-15.This document is not an ASTM standard and is intended only to prov
11、ide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the
12、standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is t
13、he responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific safety and health statements are given in Section 10.2. Referenced Documents2.1 ASTM Standards:2B953 Practice for Samplin
14、g Magnesium and Magnesium Alloys for Spectrochemical AnalysisE135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related MaterialsE158 Practice for Fundamental Calculations to Convert Intensities into Concentrations in Optical Emission SpectrochemicalAnalysis (Withdrawn 2004)3E17
15、2 Practice for Describing and Specifying the Excitation Source in Emission Spectrochemical Analysis (Withdrawn 2001)3E305 Practice for Establishing and Controlling Atomic Emission Spectrochemical Analytical CurvesE406 Practice for Using Controlled Atmospheres in Spectrochemical AnalysisE826 Practice
16、 for Testing Homogeneity of a Metal Lot or Batch in Solid Form by Spark Atomic Emission SpectrometryE876 Practice for Use of Statistics in the Evaluation of Spectrometric Data (Withdrawn 2003)3E1257 Guide for Evaluating Grinding Materials Used for Surface Preparation in Spectrochemical AnalysisE1329
17、 Practice for Verification and Use of Control Charts in Spectrochemical AnalysisE1507 Guide for Describing and Specifying the Spectrometer of an Optical Emission Direct-Reading Instrument3. Terminology3.1 DefinitionsFor definitions of terms used in this standard, test method, refer to Terminology E1
18、35.3.2 Definitions of Terms Specific to This Standard:3.2.1 binary type calibrationcalibration curves determined using binary calibrants (primary magnesium to which has beenadded one specific element).3.2.2 global type calibrationcalibration curves determined using calibrants from many different all
19、oys with considerablecompositional differences.3.2.3 alloy type calibrationcalibration curves determined using calibrants from alloys with similar compositions.3.2.4 two point drift correctionthe practice of analyzing a high and low standardant for each calibration curve and adjustingthe counts or v
20、oltage values obtained back to the values obtained on those particular standardants during the collection of thecalibration data. The corrections are accomplished mathematically and are applied to both the slope and intercept. Improvedprecision may be obtained by using a multi-point drift correction
21、 as described in Practice E1329.3.2.5 type standardizationmathematical adjustment of the calibration curves slope or intercept using a single standardant(reference material) at or close to the nominal composition for the particular alloy being analyzed. For best results the standardantbeing used sho
22、uld be within 610 % of the composition (for each respective element) of the material being analyzed.4. Summary of Test Method4.1 Aunipolar triggered capacitor discharge is produced in an argon atmosphere between the prepared flat surface of a specimenand the tip of a semi-permanent counter electrode
23、. The energy of the discharge is sufficient to ablate material from the surface ofthe sample, break the chemical or physical bonds, and cause the resulting atoms or ions to emit radiant energy. The radiant energiesof the selected analytical lines and the internal standard line(s) are converted into
24、electrical signals by either photomultiplier tubes(PMTs) or a suitable solid state detector. The detector signals are electrically integrated and converted to a digitized value. Thesignals are ratioed to the proper internal standard signal and converted into concentrations mass fractions by a comput
25、er inaccordance with Practice E158E305.4.2 Three different methods of calibration defined in 3.2.1, 3.2.2 and 3.2.3, are capable of giving equivalent precision, accuracyand detection limits.4.2.1 The first method, binary calibration, employs calibration curves that are determined using a large numbe
26、r of high-puritybinary calibrants. This approach is used when there is a need to analyze almost the entire range of magnesium alloys. Becausebinary calibrants may respond differently from alloy calibrants, the latter are used to improve accuracy by applying a slope and/orintercept correction correct
27、ion, intercept correction, or both to the observed readings.4.2.2 The second method, global calibration, employs calibration curves that are determined using many different alloycalibrants with a wide variety of compositions. Mathematical calculations are used to correct for both alloy difference an
28、dinter-element effects. Like the method above, specific alloy calibrants may be used to apply a slope and/or intercept correctioncorrection, intercept correction, or both to the observed readings.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at
29、serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.B954 1524.2.3 The third method, alloy calibration, employs calibration curves that are determined using various alloy calibrants thathave similar matrix compositions
30、. Again, specific alloy calibrants may be used to apply a slope and/or intercept correctioncorrection, intercept correction, or both to the observed readings.5. Significance and Use5.1 The metallurgical properties of magnesium and its alloys are highly dependant on chemical composition. Precise anda
31、ccurate analyses are essential to obtaining desired properties, meeting customer specifications and helping to reduce scrap due tooff-grade material.5.2 This test method is applicable to chill cast specimens as defined in Practice B953 and can also be applied to other types ofsamples provided that s
32、uitable reference materials are available.6. Interferences6.1 Table 1 lists analytical lines commonly used for magnesium analysis. Other lines may be used if they give comparableresults. Also listed are recommended concentration mass fraction range, background equivalent concentration (mass fraction
33、)(BEC), detection limits, and potential interferences where available. The values given in this table are typical; actual valuesobtained are dependent on instrument design and set-up.7. Apparatus7.1 Specimen Preparation Equipment:7.1.1 Sampling Molds, for magnesium the techniques of pouring a sample
34、 disk are described in Practice B953. Chill castsamples, poured and cast as described within Practice B953 shall be the recommended form in this test method.7.1.2 Lathe, capable of machining a smooth, flat surface on the reference materials and samples. Either alloy steel,carbide-tipped, or carbide
35、insert tool bits are recommended. Proper depth of cut and desired surface finish are described in PracticeB953.7.1.3 Milling MachineA milling machine can be used as an alternative to a lathe.7.1.4 Metallographic Polisher/GrinderA metallographic polisher/grinder may also be used to prepare the sample
36、 surfaceprovided care has been taken in the selection a non-contaminating abrasive compound. Metallographic grade wet/dry siliconcarbide discs of 120 grit or higher will produce a good sample surface with essentially no silicon carryover to the sample. Thismust be verified by making a comparison bet
37、ween freshly prepared surfaces on a polisher/grinder to that of a lathe or millingmachine. Reference Guide E1257 for a description of contamination issues with various abrasive compounds.7.2 Excitation Source, capable of producing a unipolar triggered capacitor discharge. In todays instrumentation t
38、he excitationsource is computer controlled and is normally programmed to produce: (1) a high-energy pre-burn (of some preset duration), and(2) an arc/spark-type discharge (of some preset duration) for the exposure burn during which time the analytical data is gatheredand processed by the system.7.2.
39、1 Typical parameters and exposure times are given in Table 2. It should be emphasized that the information presented isgiven as an example only and parameters may vary with respect to instrument model and manufacturer. For details on describingand specifying an excitation source, please refer to Pra
40、ctice E172.7.3 Excitation Chamber shall be designed with an upper plate that is smooth and flat so that it will mate (seal) perfectly withthe prepared surface of the sample specimen. The seal that is formed between the two will exclude atmospheric oxygen fromentering the discharge chamber. The excit
41、ation chamber will contain a mounting clamp to hold the counter electrode. Theexcitation stand assembly will also have some type of clamp or device designed to hold the sample firmly against the top plate.Some manufacturers may provide for the top plate to be liquid cooled to minimize sample heat-up
42、 during the excitation cycle. Theexcitation chamber will also be constructed so that it is flushed automatically with argon gas during the analytical burn cycle. Theexcitation chambers design should allow for a flow of argon gas to prevent the deposition of ablated metal dust on theinner-chamber qua
43、rtz window(s). The excitation chamber will be equipped with an exhaust system that will safely dispose of theargon gas and the metal dust created during the excitation cycle. For reasons of health and cleanliness, the exhausted gas and dustshould not be vented directly into the laboratory. To help w
44、ith this situation, manufacturers have designed their instruments withsome type of exhaust/filterexhaust/scrubber system to deal with this problem. The exhaust can then be vented into an efficient hoodsystem.7.4 Gas Flow System will be designed so that it can deliver pure argon gas to the excitation
45、 chamber. The purity of the argongas will affect the precision of the results. Generally, precision improves as the purity of the argon gas gets higher.Argon gas witha minimum purity of 99.995 % has been found to be acceptable. The gas shall be delivered by a flow system as described inPractice E406
46、. The argon gas source can be from high-purity compressed gas cylinders, a cryogenic-type cylinder that containsliquid argon or possibly from a central supply (liquid only). It is essential that only argon gas meeting the minimum purity of99.995 % be used. A lower purity grade of argon, such as a “w
47、elding grade,” should not be used. The delivery system shall becomposed of a two-stage type (high/low pressure) regulator of all-metal construction with two pressure gages. Delivery tubingmust not produce any contamination of the argon stream. Refrigerator grade copper tubing is recommended. The gag
48、es on theB954 153TABLE 1 Recommended Analytical LinesElement Wavelength in Air(nm)ARecommendedConcentrationMass FractionRange, %BackgroundEquivalent,%BDetectionLimit,%CInterferences Element,(nm)Aluminum 396.15 I 0.001 0.5 0.008 0.0001* Zr 396.16Aluminum 256.80 I 1.0 12.0 ZnAr256.81256.81Aluminum 266
49、.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 CeNiFe226.49226.45226.44Cadmium 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
