Optimalizace mikrostruktury permanentního magnetu na bázi Nd-Fe-B s nízkým obsahem KVZ aplikací sloučeniny Tb3Co0.6Cu0.4Hx

Abstract

Optimization of the microstructure of Nd-Fe-B-based permanent magnets prepared using strip casting was performed to increase their coercivity Hc. Matrix alloy with chemical composition (wt.%) 24.0% Nd, 6.5% Pr, 0.5% Dy, 1.0% B, 0.2 Al% was prepared by vacuum induction melting with subsequent casting on water cooled spinning wheel. The obtained powder of average size 3µm was mixed with 2 wt. % hydrogenated Tb3Co0.6Cu0.4 alloy to improve the liquid phase sintering process and increase coercivity due to the formation of continuous grain boundaries. A high resolution scanning electron microscope equipped with an energy dispersive spectrometer was used to study the microstructure, chemical and phase composition and distribution of alloying elements. From the results it can be seen that the hydrogenation of the alloy resulted in the formation of terbium hydrides TbH2 and TbH3, and a small amount of Tb3 (CoCu). A thin film was prepared using a high resolution scanning electron microscope with a focused ion beam system. A vibration sampling magnetometer was used to analyze the magnetic properties at 20 to 150 ° C. Due to the high magnetic characteristics, samples of 1x1x1 mm were used. A specially designed Zeiss microscope was used to visualize magnetic domain patterns on the surface of magnetic materials using magneto-optical Kerr microscopy. Fine star-like domains are typical surface domains that are detected in perpendicular anisotropy systems. However, the shape of the domains varies at different locations on the surface, suggesting inhomogeneous local magnetic properties of the magnet.