Study on magnetic properties and demagnetization process of the c-plane in the grain boundary diffusion magnet

•Micromagnetic simulation is used to simulate magnetic properties of grain boundary diffusion.•After diffusing Tb in the edge area, the amount of Tb was reduced 58% and ΔHcj/wt.% Tb increased 63%.•Diffusing Tb in the edge area of the c-planes has a positive effect on Hcj and ΔHcj/wt.% Tb.•The demagnetization process is from the edge area to the center area on the c-planes.