Solidification microstructure selection of the peritectic Nd-Fe-B alloys

Bridgman directional solidification and laser remelting experiments were carried out on Nd_11.76Fe_82.36B_5.88 and Nd_13.5Fe_79.75B_6.75 alloys. Microstructure evolutions along with solidification parameters (temperature gradient G, growth velocity V and initial alloy composition C ₀) were investigated. A solidification microstructure selection map was established, based on the consideration of solidification characteristics of peritectic T₁ phase. In Bridgman directional solidification experiments, with the increasing growth velocities, the morphology of T₁ phase changed from plane front or faceted plane front to dendrites. In laser remelting experiments, a transition from primary γ-Fe dendrites to T₁ dendrites was found. Theoretical predictions are in good agreement with experimental results. Supported by the National Natural Science Foundation of China (Grant No. 50395100)