ASTM_A_1101_-_16.pdf

Designation:A110116Standard Specification forSintered and Fully Dense Neodymium Iron Boron(NdFeB)Permanent Magnets1This standard is issued under the fixed designation A1101;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,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 specification covers technically important,com-mercially available,magnetically hard sintered and fully denseneodymium iron boron(Nd2Fe14B,NdFeB,or“Neo”)perma-nent magnets.These materials are available in a wide range ofcompositions with a commensurately large range of magneticproperties.The numbers in the Nd2Fe14B name indicate theapproximate atomic ratio of the key elements.1.2 Neodymium iron boron magnets have approximatemagnetic properties of residual magnetic induction,Br,from1.08 T(10 800 G)up to 1.5 T(15 000 G)and intrinsic coercivefield strength,HcJ,of 875 kA/m(11 000 Oe)to above 2785kA/m(35 000 Oe).Special grades and isotropic(un-aligned)magnets can have properties outside these ranges(see Appen-dix X4).Specific magnetic hysteresis behavior(demagnetiza-tion curve)can be characterized using Test Method A977/A977M.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses are mathematicalconversions to customary(cgs-emu and inch-pound)unitswhich are provided for information only and are not consideredstandard.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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2A340 Terminology of Symbols and Definitions Relating toMagnetic TestingA977/A977M Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials Using Hyster-esigraphs2.2 Other Standards:MMPA Standard No.0100-00 Standard Specifications forPermanent Magnet Materials3IEC 60404-8-1 Magnetic Materials Part 8:Specifications forIndividual Materials Section 1 Standard Specificationsfor Magnetically Hard Materials43.Terminology3.1 The terms and symbols used in this specification,unlessotherwise noted,are defined in Terminology A340.3.2 Terms that are not defined in Terminology A340 but arein common usage and used herein are as follows.3.2.1 Recoil permeability,(rec),is the permeability corre-sponding to the slope of the recoil line.For reference seeincremental,relative,and reversible permeabilities as definedin Terminology A340.In practical use,this is the slope of thenormal hysteresis loop in the second quadrant and in proximityto the B-axis.The value of recoil permeability is dimension-less.Note that in producers product literature recoil perme-ability is sometimes represented by the symbol r,which isdefined by Terminology A340 as relative permeability.3.2.2 Magnetic characteristics change with temperature.Two key metrics of permanent magnet performance are re-sidual induction,Br,and intrinsic coercive field strength,HcJ.The change in these characteristics over a defined and limitedtemperature range can be reversible,that is,nondestructive.This change is represented by values called reversible tempera-ture coefficients.The symbol for reversible temperature coef-ficient of induction is(Br)and of(intrinsic)coercivity is(HcJ).They are expressed in percent change per degreeCelsius,%/C,or the numerically equivalent percent perKelvin,%/K,and represent the average rate of change of the1This specification is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A06.02 onMaterial Specifications.Current edition approved Nov.1,2016.Published November 2016.DOI:10.1520/A1101162For 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.3Available from the Permanent Magnet Division of the SMMA(www.sm-ma.org).It was previously available from The International Magnetics Association(IMA).The IMA had been the successor to the MMPA and both organizations(MMPA and IMA)no longer exist.4Available from International Electrotechnical Commission(IEC),3,rue deVaremb,1st Floor,P.O.Box 131,CH-1211,Geneva 20,Switzerland,http:/www.iec.ch.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 characteristic within the specified temperature range.Thechange in magnetic characteristics is nonlinear,so it is neces-sary to specify the temperature range over which the coefficientapplies.3.2.3 The maximum recommended working temperature ofa permanent magnet,Tw,is a semi-arbitrary value sometimesassigned by ma