Mechanism of texture enhancement in nanocomposite magnets during process of die upsetting coupled with Nd-Cu grain boundary diffusion

The microstructure of die-upset nanocomposite magnets with different height reduction was studied to investigate the mechanism of texture development in processes of die upsetting coupled with Nd-Cu grain boundary diffusion. At beginning stage of die upsetting process, inhomogeneous Nd-Cu grain boundary diffusion results in two kinds of different grain boundary microstructures. As for adjacent grains with grain boundary phase, the stress-induced solution-precipitation underlies the formation of the platelet-shaped grains and texture enhancement. Whereas there are two types of texture enhancement for the neighboring grains without grain boundary phase: grain boundary sliding and grain devouring. As die upsetting further proceeds, the stress-induced solution precipitation is the dominant mechanism for texture enhancement due to fuller Nd-Cu grain boundary diffusion.