Calculation of remanence and degree of texture from EBSD orientation histograms and XRD rocking curves in Nd–Fe–B sintered magnets

Abstract

Sintered Nd–Fe–B permanent magnets with different composition and texture have been characterized by electron backscattered diffraction (EBSD) and X-ray diffraction (XRD) techniques. Instead of EBSD mapping on a microscopic scale, smooth orientation histograms were obtained with the EBSD sampling method. In this method 45,000 single orientation measurements were taken with a step size of 10µm, which is here above the average grain size of the Nd2Fe14B grains. Complementary macroscopic texture information was extracted from XRD rocking curves. In order to test the statistical reliability of the EBSD and XRD measurements, the remanences along the easy and the hard directions were calculated from this data by means of a simple approach assuming magnetically decoupled grains, identical in size, and absence of domain walls. For this, the saturation magnetization has to be approximated or one can employ the degree of texture using two different common definitions of this parameter. Both definitions are independently of the saturation magnetization. The calculated degrees of texture compare well with the magnetic measurements, which demonstrate the excellent statistical reliability of the EBSD and XRD data. Furthermore, it shows that the three assumptions above reproduce well the characteristics of sintered Nd–Fe–B magnets.