Wettability between Nd₂Fe₁₄B and Nd-Rich Phase in Nd-Fe-B Alloy System

Abstract

  The wettability between Nd₂Fe₁₄B and Nd-rich phases has been investigated through the sessile drop method. The compositions of prepared Nd-rich ingots were Nd_72.0Fe_26.1B_1.9 (ternary) and Nd₇₂Fe_22.4Cu_3.7B_1.9(Cu-added). Nd-rich ingots were cut and put on a polished Nd₂Fe₁₄B plate and heated in a furnace. Contact angles between Nd₂Fe₁₄B plate and Nd-rich ingots were measured as a parameter of wettability under controlled temperature. For the Cu added sample, both contact angles in all temperature range and temperatures when contact angle starts to change were lower than those for ternary sample. These results indicate Cu substitution yields improvement of wettability. DTA measurements for two Nd-rich ingots reveal that their contact angles starts to change at lower temperature than their melting points It is considered that those phenomena are derived from the existence of Nd₂Fe₁₄B/Nd-rich interface.