Niobium wires as space holder and sintering aid for porous NiTi

When NiTi powder compacts containing Nb wires are heated above 1170°C, each Nb wire reacts with adjacent NiTi powders to form a eutectic liquid which wicks into the space between the remaining NiTi powders. This creates a macropore at the location of the Nb wire while eliminating the microporosity between NiTi powders which is filled with a NiTi/Nb eutectic phase after solidification. This novel method produces - in a single step and without applied pressure - a dense NiTi matrix with elongated pores suitable for shape memory or superelastic applications such as bone implants, dampeners and actuators. Porous NiTi consisting of a dense NiTi matrix containing 3D-connecting, elongated pores is produced by a single step heat-treatment without applied pressure. When NiTi powder compacts containing Nb wires are heated above 1170°C, each Nb wire reacts with adjacent NiTi powders to form eutectic liquid which wicks into the space between the remaining NiTi powders. The location of the Nb wire becomes a macropore while the microporosity between NiTi powders is eliminated.