ASTM A1101-23 - Standard Specification for Sintered and Fully Dense Neodymium Iron Boron (NdFeB) Permanent Magnets

1.1 This specification covers technically important, commercially available, magnetically hard sintered and fully dense neodymium iron boron (Nd₂Fe₁₄B, NdFeB, or “Neo”) permanent magnets. These materials are available in a wide range of compositions with a commensurately large range of magnetic properties. The numbers in the Nd₂Fe₁₄B name indicate the approximate atomic ratio of the key elements.

1.2 Anisotropic (aligned) sintered and fully dense neodymium iron boron magnets have approximate magnetic properties of residual magnetic induction, B_r, from 1.08 T
(10 800 G) up to 1.5 T (15 000 G) and intrinsic coercive field strength, H_cJ, of 875 kA/m (11 000 Oe) to above 2785 kA/m (35 000 Oe). Fully dense but not sintered magnets include hot-deformed magnets using a plastic deformation technique, such as upsetting or extrusion, at elevated temperatures for the crystallographic alignment, as opposed to magnetic field alignment in sintered magnets. Special grades and isotropic (un-aligned) magnets can have properties outside these ranges (see Appendix X4). Specific magnetic hysteresis behavior (demagnetization curve) can be characterized using Test Method A977/A977M.

1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to customary (cgs-emu and inch-pound) units which are provided for information only and are not considered standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.