Defects and cellular structure evolution in Sm2Co17-type magnet: The role of phase transformation

TEM specimens were prepared by mechanical thinning to ~50 μm, followed by final ion milling (Gatan PIPS, operating voltage 4 kV) to electron transparency. High-angle annular dark-field (HAADF-STEM) imaging was used to observe the morphology and phase distribution of cellular structures, and selected-area electron diffraction (SAED) was employed to identify the crystal structures of different phases. X-ray diffraction (XRD, model Bruker D8 Advance, Cu Kα radiation) was used for phase analysis.

Magnetic properties were measured at room temperature using a vibrating sample magnetometer (VSM, model Lake Shore 8600, maximum field 3 T) to obtain hysteresis loops, from which remanence, coercivity, and maximum energy product were derived.The dataset covers microstructural images, crystallographic data, and magnetic performance data for samples with different Fe contents (17.5 wt%, 19.5 wt%, 21.5 wt%) and various aging times (5–50 h).

The spatial resolution is at the nanoscale (TEM image pixel resolution ~0.1 nm/pixel, HAADF-STEM ~0.05 nm/pixel); aging temperature is 840 °C, with time spans from 5 to 50 h and a time resolution of 5–10 h. The dataset specifically includes the following files:TEM_Images: Contains bright-field images, HAADF-STEM images, and SAED patterns for observing cellular morphology, cell size, cell-wall continuity, and defect distribution.

File formats are .tif or .dm3 (DigitalMicrograph proprietary format, readable by Gatan DigitalMicrograph software; official download: gatan.com/).XRD_Data: Raw X-ray diffraction data in .raw or .txt format, including 2θ angles (10°–90°, step 0.02°) and corresponding diffraction intensities, used for phase identification and crystal structure analysis.Magnetic_Properties: Excel spreadsheet (.xlsx) containing approximately 60 records (6 aging times × 3 Fe contents × 3–5 parallel samples).

Row labels are sample IDs (e.g., Fe17.5_10h_01), and column labels include: Fe content (wt%), aging time (h), remanence B_r (T), coercivity H_cj (kOe), maximum energy product (BH)_max (MGOe), and squareness H_k/H_cj. All magnetic data have been calibrated against standard Nd-Fe-B reference samples, with measurement errors controlled within ±2%.EDS_Mapping: Elemental distribution maps and line-scan data in .emd or .txt format, containing distribution information for Sm, Co, Fe, Cu, and Zr, used to analyze elemental diffusion and segregation during aging.There are no missing data.

The main source of error in microstructural characterization data arises from the local representativeness of TEM specimens; at least five different fields of view are observed and counted for each sample, and the statistical error in cell size measurement is approximately ±5%. Magnetic measurement errors mainly originate from the VSM instrument's systematic error (±1%) and sample weighing error (±0.5%).

XRD data are angle-corrected using standard Si powder, with 2θ angle errors within ±0.02°.