1、Designation: E 821 96 (Reapproved 2003)Standard Practice forMeasurement of Mechanical Properties During Charged-Particle Irradiation1This standard is issued under the fixed designation E 821; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year 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.PART IEXPERIMENTAL PROCEDURE1. Scope1.1 This practice covers the performance of mechanicaltests on materials
3、 being irradiated with charged particles. Thesetests are designed to simulate or provide understanding of, orboth, the mechanical behavior of materials during exposure toneutron irradiation. Practices are described that govern the testmaterial, the particle beam, the experimental technique, and thed
4、amage calculations. Reference should be made to otherASTM standards, especially Practice E 521. Procedures aredescribed that are applicable to creep and creep rupture testsmade in tension and torsion test modes.21.2 The word simulation is used here in a broad sense toimply an approximation of the re
5、levant neutron irradiationenvironment. The degree of conformity can range from poor tonearly exact. The intent is to produce a correspondencebetween one or more aspects of the neutron and chargedparticle irradiations such that fundamental relationships areestablished between irradiation or material
6、parameters and thematerial response.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 applica-bility of regulatory limi
7、tations prior to use.2. Referenced Documents2.1 ASTM Standards:E 170 Terminology Relating to Radiation Measurementsand Dosimetry3E 521 Practice for Neutron Radiation Damage Simulationby Charged-Particle Irradiation33. Terminology3.1 Definitions:3.1.1 Descriptions of relevant terms are found in Termi
8、nol-ogy E 170.4. Specimen Characterization4.1 Source Material Characterization:4.1.1 The source of the material shall be identified. Thechemical composition of the source material, as supplied by thevendor or of independent determination, or both, shall bestated. The analysis shall state the quantit
9、y of trace impurities.The material, heat, lot, or batch, etc., number shall be stated forcommercial material. The analytical technique and composi-tional uncertainties should be stated.4.1.2 The material form and history supplied by the vendorshall be stated. The history shall include the deformatio
10、nprocess (rolling, swaging, etc.), rate, temperature, and totalextent of deformation (given as strain components or geometri-cal shape changes). The use of intermediate anneals duringprocessing shall be described, including temperature, time,environment, and cooling rate.4.2 Specimen Preparation and
11、 Evaluation:4.2.1 The properties of the test specimen shall represent theproperties of bulk material. Since thin specimens usually willbe experimentally desirable, a specimen thickness that yieldsbulk properties or information relatable to bulk propertiesshould be selected. This can be approached th
12、rough either oftwo techniques: (1) where the test specimen properties exactlyequal bulk material properties; (2) where the test specimenproperties are directly relatable to bulk properties in terms ofdeformation mechanisms, but a size effect (surface, texture,etc.) is present. For the latter case, t
13、he experimental justifica-tion shall be reported.4.2.2 The specimen shape and nominal dimensions shall bestated and illustrated by a drawing. Deviations from ASTMstandards shall be stated. The dimensional measurement tech-niques and the experimental uncertainty of each shall be stated.The method of
14、specimen preparation, such as milling, grinding,etc., shall be stated. The degree of straightness, flatness, surfacecondition, edges, fillets, etc., shall be described. The method of1This practice is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applications and is the direct
15、 responsibility of SubcommitteeE10.08 on Procedures for Neutron Radiation Damage Simulation.Current edition approved Jan. 10, 1996. Published March 1996. Originallypublished as E 821 81. Last previous edition E 821 89.2These practices can be expanded to include mechanical tests other than thosespeci
16、fied as such experiments are proposed to Subcommittee E10.08.3Annual Book of ASTM Standards, Vol 12.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.gripping the specimen during the test shall be stated and,preferably, illustrated
17、by a drawing.4.2.3 The heat treatment conditions such as time, tempera-ture, atmosphere, cooling rate, etc., shall be stated. Because ofthe small specimen dimensions, it is essential to anneal in anon-contaminating environment. Reanalysis for O, N, C, andother elements that are likely to change in c
18、oncentration duringheat treatment is recommended.4.2.4 Special care shall be exercised during specimen prepa-ration to minimize surface contamination and irregularitiesbecause of the possible effect the surface can have on the flowproperties of small specimens. Visible surface contaminationduring he
19、at treatment shall be reported as a discoloration or,preferably, characterized using surface analysis technique. It isrecommended that surface roughness be characterized.4.2.5 The preirradiation microstructure shall be thoroughlyevaluated and reported, including grain size, grain shape,crystallograp
20、hic texture, dislocation density and morphology,precipitate size, density, type, and any other microstructuralfeatures considered significant. When reporting TEM results,the foil normal and diffracting conditions shall be stated. Thespecimen preparation steps for optical and transmission elec-tron m
21、icroscopy shall be stated.4.2.6 The preirradiation mechanical properties shall be mea-sured and reported to determine deviations from bulk behaviorand to determine baseline properties for irradiation measure-ments. It is recommended that creep rates be measured for eachspecimen before and after irra
22、diation (see section 3.4 for moredetail). The thermal creep rate shall be obtained under condi-tions as close as possible to those existing during irradiation.The temperature, strain rate, atmosphere, etc., shall be stated.4.2.7 It is recommended that other material propertiesincluding microhardness
23、, resistivity ratio, and density be mea-sured and reported to improve interlaboratory comparison.4.3 Irradiation Preconditioning:4.3.1 Frequently the experimental step preceding charged-particle irradiation will involve neutron irradiation or heliumimplantation. This section contains procedures that
24、 character-ize the environment and the effects of this irradiation precon-ditioning. For reactor irradiations the reactor, location inreactor, neutron flux, flux history and spectrum, temperature,environment, and stress shall be reported. The methods ofdetermining these quantities shall also be repo
25、rted. The dis-placement rate (dpa/s) and total displacement (dpa) shall becalculated; see Practice E 521 for directions. For ex-reactorneutron irradiation the accelerator, neutron flux and spectrum,temperature, environment, and stress shall be stated, includingdescriptions of the measurement techniq
26、ues. The dpa/s and dpashould be calculated (see Sections 7-10). For helium implan-tation using an accelerator, the accelerator, beam energy andcurrent density, beam uniformity, degrader system, tempera-ture, environment, stress, helium content, and helium measure-ment technique and any post-implanta
27、tion annealing shall bestated. The helium distribution shall be calculated as shall theresulting dpa (or shown to be negligible); see Sections 7 and 8and Practice E 521 for assistance. If another helium implanta-tion technique is used, a description shall be given of thetechnique. It is recommended
28、that chemical analysis followany of the above preconditioning procedures.4.3.2 The microstructure of irradiation preconditioned ma-terial shall be characterized with respect to dislocation loopsize and density, total dislocation density, voids, and anymicrostructural changes from the unirradiated co
29、ndition.Specimen density changes or dimensional changes shall bereported. It is recommended that changes in hardness or tensilestrength, or both, be reported. Furthermore, any change insurface condition, including coloration, shall be reported.4.4 Analysis After Charged-Particle Irradiation:4.4.1 Th
30、e physical, mechanical, and chemical properties ofthe specimen should be characterized prior to irradiation andany irradiation-induced changes reported. Practice E 521 pro-vides information on post-irradiation specimen preparation andexamination.4.4.2 After charged-particle irradiation, the specimen
31、 di-mensions and density shall be measured. The microstructureand surface conditions shall be reexamined, with changesbeing reported. Chemical analysis for those elements likely tochange during the mechanical test (O, C, N, H) shall beperformed on the test specimen or on a dummy specimen heldunder c
32、onditions closely approximating those during irradia-tion. It is recommended that changes in hardness, tensilestrength, or creep strength, or both, be measured and reported.5. Particle Beam Characterization5.1 Beam Composition and Energy:5.1.1 Most accelerator installations include a calibratedmagne
33、tic analysis system which ensures beam purity andprovides measurement and control of the energy and energyspread, both of which should be reported. A possible exceptionwill occur if analogue beams are accelerated. For example, acyclotron can produce simultaneous beams of16O4+(Z/A =14)and12C3+(Z/A =1
34、4) at different energies (E + EoZ2/A) whichcannot easily be separated magnetically or electrostatically.This situation, normally only significant for heavy ion beams,can be avoided by judicious choice of charge state and energy.For Van de Graaff accelerators analogue beams of light ions,such as D+an
35、d He+, can be generated, and under certaincircumstances involving two stage acceleration and furtherionization (for example, He+ 5 MeV He+ 5 MeV He+),beams of impurity ions can be produced that may not be easilyseparated from the primary beam (for example, 5 MeV H+).5.1.2 For most cases, ion sources
36、 are sufficiently pure toremove any concern of significant beam impurity, but thisproblem should be considered. Beam energy attenuation andchanges in the divergence of the beam passing throughwindows and any gaseous medium shall be estimated andreported.5.2 Spatial Variation in Beam Intensity:5.2.1
37、The quantity of interest is beam intensity/unit area atthe specimen. It is usually desirable to produce a uniform beamdensity over the specimen area so that this quantity can beinferred from a measurement of the total beam intensity andarea.5.2.2 Total beam intensity should be measured using aFarada
38、y cup whenever possible; however, this may not bepossible on a continuous basis during irradiation. The FaradayE 821 96 (2003)2cup shall be evacuated to P RpE/4! (2)RdE! 2RpE/2!. (3)Since these expressions are derived from an electronicstopping power equation (11) (that is, Bethe Bloch formulism),th
39、ey are valid to the extent the electronic stopping powerapproximates the total stopping power. Agreement with tabularvalues is within 5 % for deuteron energies greater than 2 MeVand alpha particle energies above 8 MeV and improves withenergy. Generally, these errors will be tolerable in view of thef
40、act that end of range is usually avoided in mechanical propertytesting. It is near end of range that the stopping power isvarying most rapidly and the energy and range straggling isgreatest. Furthermore, it is near end of range that the influenceof foreign atoms introduced by ions coming to rest wil
41、l begreatest.10. Damage Calculations10.1 In calculations involving light ion radiation damage, itis recommended that models consistent with those recom-mended for use in calculating neutron damage be used wher-ever practical. Therefore, consistency in the choice of energypartition theory and seconda
42、ry displacement models will berecommended and discussed in this section. More detail incertain areas can be obtained by consulting Practice E 521.10.1.1 It is likely that mechanical property testing may beconducted at some future date using energetic electrons, lightions with E 100 MeV, or very ener
43、getic heavy ions (A 4).It is anticipated that as experimental techniques using theseparticles evolve, the standards will be amended to includedamage calculations covering them.10.2 Damage Regimes:10.2.1 The interaction between an energetic light ion (E 1MeV) and target nuclei has generally been assu
44、med to be dueto pure Coulomb scattering, leading to the Rutherford scatter-ing cross section for purposes of calculating displacementdamage. This is only true, however, over a limited region ofparticle energy and energy transfer where the limits of validityare determined by both the incident light i
45、on and targetmaterial. For small energy transfers or low energies, or both,the electronic screening of the nuclei becomes important. Asufficient criteria for the neglect of screening corresponds to(12):E . Es; 0.4A1/A2!Z12Z22Z12/31 Z22/3! 3 leV/Ed!MeV (4)Recommended values of Edhave been tabulated i
46、n PracticeE 521, Table 1. Representative values of Esfor several mate-rials are listed in Table 1 of this practice. In practice, theinfluence of screening may be neglected at somewhat lowerenergies depending upon accuracy desired. As an approximaterule, the screening correction to the damage is less
47、 than 5 % ifE Es/5. For large energy transfers or high energy, or both,nuclear forces may cause deviations from Rutherford scatter-ing. The energy, in megaelectronvolts, where nuclear forcesbecome significant is approximated by the coulomb barrier andis of the order of:EcZ1Z2A11/31 A21/3(5)Represent
48、ative values of Ecare given in Table 2.TABLE 1 Values of the Screening Energy, Es, MeVMaterial 1p11d22He32He4Al 0.82 1.6 11 14Cu 2.9 5.8 37 49Ag 5.5 11 68 91Au 7.0 14 87 120E 821 96 (2003)6Therefore, the expression:Es, E , Ec(6)establishes a criterion for the use of Rutherford scattering. Insome cas
49、es Es Ec(for example, alpha particles on copper) inwhich case there are deviations from Rutherford scattering forsmall and large energy transfers. In general, however, there isa limited energy range over which Rutherford scattering maybe assumed. Later sections will discuss in greater detail thecalculation of displacement damage in cases where Rutherfordscattering is inappropriate.10.3 Primary Recoil Spectrum:10.3.1 It is recommended that the primary recoil spectrumbe adopted as an interim measure of the degree by which lightions simulate neutrons. Other parameters suc
