This specification applies to technically important, commercially available, magnetically hard sintered (fully dense) permanent magnets commonly known as samarium cobalt (SmCo). SmCo permanent magnets are available in two general composition families abbreviated ‘SmCo 1:5’ and ‘SmCo 2:17.’ These materials have approximate magnetic properties of residual magnetic induction from 0.78 T (7800 G) to 1.18 T (11 800 G) and intrinsic coercivity typically greater than 800 kA/m (10 000 Oe). Special grades and isotropic (un-aligned) magnets can have properties outside these ranges. Specific magnetic hysteresis behavior (demagnetization curve) can be characterized using Test Method A977/A977M.

This specification includes requirements for the chemical composition of SmCo permanent magnets as well as their physical and mechanical properties, magnetic properties (maximum energy product, residual induction, coercive field strength, intrinsic coercive field strength), workmanship, finish, and appearance. It also covers sampling, certification, and packaging and package marking.

1.1 This specification covers technically important, commercially available, magnetically hard sintered (fully dense) permanent magnets commonly known as samarium cobalt. These materials are available in two general composition families abbreviated “SmCo 1:5” and “SmCo 2:17.” The numbers indicate the approximate atomic ratio of samarium to the sum of other constituents. (Refer to Appendix X3 for additional composition information.)

1.2 Samarium cobalt magnets have approximate magnetic properties of residual magnetic induction, B_r, from 0.78 T (7800 G) to 1.18 T (11 800 G) and intrinsic coercivity, H_cJ, typically greater than 800 kA/m (10 000 Oe). 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 and health practices and determine the applicability of regulatory limitations prior to use.