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

Abstract

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.