1、Designation: E821 16Standard Practice forMeasurement of Mechanical Properties During Charged-Particle Irradiation1This standard is issued under the fixed designation E821; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.PART IEXPERIMENTAL PROCEDURE1. Scope1.1 This practice covers the performance of mechanicaltests on materials being irradiated wit
3、h charged particles.Thesetests are designed to provide an understanding of the effects ofneutron irradiation on the mechanical behavior of materials.Practices are described that govern the test material, theparticle beam, the experimental technique, and the damagecalculations. Reference should be ma
4、de to other ASTMstandards, especially Practice E521. Procedures are describedthat are applicable to creep and creep rupture tests made intension and torsion test modes.21.2 The word simulation is used here in a broad sense toimply an approximation of the relevant neutron irradiationenvironment. The
5、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 parameters and thematerial response.1.3 The
6、 values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 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-priat
7、e safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E170 Terminology Relating to Radiation Measurements andDosimetryE521 Practice for Neutron Radiation Damage Simulation byCharged-Particle Irradiation3. Term
8、inology3.1 Definitions:3.1.1 Descriptions of relevant terms are found in Terminol-ogy E170.4. 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
9、 determination, or both, shall bestated. The analysis shall state the quantity 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 su
10、pplied by the vendorshall be stated. The history shall include the deformationprocess (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
11、 temperature, time,environment, and cooling rate.4.2 Specimen Preparation and 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 informat
12、ion relatable to bulk propertiesshould be selected. This can be approached through either of1This practice is under the jurisdiction of ASTM Committee E10 on NuclearTechnology and Applications and is the direct responsibility of SubcommitteeE10.08 on Procedures for Neutron Radiation Damage Simulatio
13、n.Current edition approved Oct. 1, 2016. Published December 2016. Originallyapproved in 1981. Last previous edition approved in 2009 as E821 96 (2009).DOI: 10.1520/E0821-16.2These practices can be expanded to include mechanical tests other than thosespecified as such experiments are proposed to Subc
14、ommittee E10.08.3For 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.Copyright ASTM International, 100 Barr Harbor
15、 Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1two 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 (sur
16、face, texture,etc.) is present. For the latter case, the 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 experimen
17、tal uncertainty of each shall be stated.The method of specimen preparation, such as milling, grinding,etc., shall be stated.The degree of straightness, flatness, surfacecondition, edges, fillets, etc., shall be described. The method ofgripping the specimen during the test shall be stated and,prefera
18、bly, illustrated by a drawing.4.2.3 The heat treatment conditions such as time,temperature, atmosphere, cooling rate, etc., shall be stated.Because of the small specimen dimensions, it is essential toanneal in a non-contaminating environment. Reanalysis for O,N, C, and other elements that are likely
19、 to change in concen-tration during heat 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 conta
20、minationduring heat 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 sh
21、ape,crystallographic 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 transmi
22、ssion elec-tron microscopy 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 befo
23、re and after irradiation. The thermal creep rateshall be obtained under conditions as close as possible to thoseexisting during irradiation. The temperature, strain rate,atmosphere, etc., shall be stated.4.2.7 It is recommended that other material propertiesincluding microhardness, resistivity ratio
24、, 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 character-ize the
25、environment and the effects of this irradiation precon-ditioning. For reactor irradiations the reactor, location inreactor, neutron flux (fluence rate), flux history and spectrum,temperature, environment, and stress shall be reported. Themethods of determining these quantities shall also be reported
26、.The displacement rate (dpa/s) and total displacement (dpa)shall be calculated; see Practice E521 for directions. Forex-reactor neutron irradiation the accelerator, neutron flux andspectrum, temperature, environment, and stress shall be stated,including descriptions of the measurement techniques. Th
27、edpa/s and dpa should be calculated (see Sections 710). Forhelium implantation using an accelerator, the accelerator, beamenergy and current density, beam uniformity, degrader system,temperature, environment, stress, helium content, and heliummeasurement technique and any post-implantation annealing
28、shall be stated. The helium distribution shall be calculated asshall the resulting dpa (or shown to be negligible); see Sections7 and 8 and Practice E521 for assistance. If another heliumimplantation technique is used, a description shall be given ofthe technique. It is recommended that chemical ana
29、lysis 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 condition.Specimen
30、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 The physical, mecha
31、nical, and chemical properties ofthe specimen should be characterized prior to irradiation andany irradiation-induced changes reported. Practice E521 pro-vides information on post-irradiation specimen preparation andexamination.4.4.2 After charged-particle irradiation, the specimen di-mensions and d
32、ensity 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 conditions closely
33、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 calibratedmagnetic analysis syste
34、m which ensures beam purity andprovides measurement and control of the energy and energyspread, both of which should be reported.Apossible exceptionwill occur if analogue beams are accelerated. For example, acyclotron can produce simultaneous beams of16O4+(Z/A =14)and12C3+(Z/A =14) at different ener
35、gies (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+and He+, can be genera
36、ted, 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 are sufficiently pu
37、re toremove any concern of significant beam impurity, but thisE821 162problem 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 The quantity
38、 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 aFaraday cup whenev
39、er possible; however, this may not bepossible on a continuous basis during irradiation. The Faradaycup shall be evacuated to P RpE/4! (2)RdE!2RpE/2!. (3)Since these expressions are derived from an electronicstopping power equation (12) (that is, Bethe Bloch formulism),they are valid to the extent th
40、e 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 thefact that end of range is usual
41、ly 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 will begreatest.10. Damage Calcul
42、ations10.1 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 practicable (13). Therefore, consistency in the choice ofenergy partition theory and secondary displacement modelsw
43、ill be recommended and discussed in this section. More detailin certain areas can be obtained by consulting Practice E521.10.1.1 It is likely that mechanical property testing may beconducted at some future date using energetic electrons, lightions with E 100 MeV, or very energetic heavy ions (A 4).I
44、t 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 assumed to be dueto pure Cou
45、lomb 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 ion and targetmaterial. F
46、or 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(14):E.Es;0.4A1/A2!Z12Z22Z12/31Z22/3! 3 leV/Ed!MeV (4)Recommended values of Edhave been tabulated in PracticeE521,Table 1. Repr
47、esentative values of Esfor several materialsare listed in Table 1 of this practice. In practice, the influenceof screening may be neglected at somewhat lower energiesdepending upon accuracy desired. As an approximate rule, thescreening correction to the damage is less than 5 % if E Es/5.For large en
48、ergy transfers or high energy, or both, nuclearforces may cause deviations from Rutherford scattering. TheE821 166energy, in megaelectronvolts, where nuclear forces becomesignificant is approximated by the coulomb barrier and is of theorder of:EcZ1Z2A11/31A21/3(5)Representative values of Ecare given
49、 in Table 2.Therefore, the expression:Es,E,Ec(6)establishes a criterion for the use of Rutherford scattering. Insome cases 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 primar
