Fabrication of Lotus-Type Porous Ni₃Al with and without Boron

Abstract

Ni₃Al with and without boron was melted and unidirectionally solidified in pressurized hydrogen atmosphere by using a continuous zone melting method. For Ni₃Al without boron, cylindrical pores elongated in the direction parallel to the solidification direction, are formed in Ni₃Al matrix. On the other hand, no pore is formed in Ni₃Al with 0.23 mol% B solidified under the same condition. This result suggests that the solubility gap of hydrogen between liquid and solid Ni₃Al with boron is extremaly small.