Fundamentals of the HDDR treatment of Nd2Fe14B type alloys

There are generalized experimental data on the kinetics of direct and reverse hydrogen-induced diffusive phase transformations in Nd2Fe14B type alloys, which is the basis of the HDDR technology. Their most general mechanisms, types of isothermal kinetic diagrams characteristic of both direct and reverse HIDP transformations, and mechanism of temperature influence on the kinetics are discussed. A conclusion is drawn that temperature (in parallel with hydrogen) is not only a necessary thermodynamic factor, but the most important kinetic factor characterizing general features of HIDP transformations. (C) 2003 Elsevier B.V. All rights reserved.