Effect of B Content on Sintering Behavior of Nd–Fe–B Ternary Alloy Powder

Abstract

Effects of B content on the sintering behavior of Nd₁₅Fe_85−xB_x (x=4–10 at%) alloy powders were investigated through microstructural observations, and measurements of DTA, linear shrinkage and magnetic properties. In the case of x≥6 at%, a liquid phase forms from ternary eutectic reaction of Nd-rich, Nd₂Fe₁₄B and Nd_1.1Fe₄B₄ phases at 938 K. While the shrinkage below 1300 K is very small because of a lack in the amount of liquid phase, remarkable shrinkage occurs when the sintering temperature is raised above 1300 K. On the other hand, in the case of x2Fe₁₇ phases at 963 K. In this case, shrinkage starts rapidly corresponding to the appearance of liquid phase and continues at a constant rate to higher temperatures. This is probably due to increase of the amount of liquid phase and the reaction between Nd₂Fe₁₇ and Nd₂Fe₁₄B phases, causing the liquid flow and solution-precipitation.