Effect of Al content on porous Ni–Al alloys

Porous Ni–Al alloys with different nominal compositions ranging from Ni–10 wt.% Al to Ni–40 wt.% Al were fabricated through reactive synthesis of Ni and Al elemental powders. It had been found that the volume expansion, maximum pore size and permeability of porous Ni–Al alloys increased with increasing the Al content, indicating that the nature of the pores can be manipulated through changing the Al content. In addition, detailed structural characterizations showed that the fabricated porous Ni–Al alloys can have three crystalline phases (i.e., Ni3Al, NiAl, and Ni2Al3) when using different compositions, in good agreement with the Ni–Al phase diagram. Mechanical strength tests of the fabricated porous Ni–Al alloys were also performed. Both of the bending strength and tensile strength of porous Ni–Al alloys were in the range of 5–80 MPa, and decreased with increasing the Al content.