Neodymium magnets include sintered NdFeB magnet and bonded NdFeB magnet.
Sintered NdFeB magnets, i.e. sintered neodymium iron boron magnets, are those permanent magnetic materials that based on a Nd-Fe-B tetragonal crystal structure, and they are manufactured through a powder metallurgy (PM) process. They contain three basic elements neodymium, iron and boron. The neodymium element can be substituted by a portion of other rare earth elements (REEs) including praseodymium (Pr), dysprosium (Dy), terbium (Tb), cerium (Ce), etc. The iron element can be substituted by a portion of cobalt (Co) element to increase the magnets' Curie temperature (Tc), thermal stability and corrosion resistance. In order to control the microstructure and the microchemistry so as to meet required performance, it also adds a small portion of other metal elements including aluminium (Al), copper (Cu), niobium (Nb), gallium (Ga), etc.
This website describes the basic composition and microstruction of sintered NdFeB magnet: Introduction to Basic Composition and Microstructure of Sintered NdFeB Magnet
Bonded NdFeB magnets, i.e. bonded neodymium iron boron magnets, are those permanent magnetic materials made of rapid quenched NdFeB magnetic powders combined with resin binders (epoxy, Nylon/polyamide (PA), polyphenylene sulfide (PPS), etc). They are manufactured through a bonded process (compression, injection, extrusion or calendaring molding), so it is available to obtain complex geometries with high dimensional precision. Controlling the performance and proportion of NdFeB magnetic powders, it is able to adjust the magnets' magnetic properties in a continuous range.