Pore formation mechanism of porous Ni-Cr-Al alloys prepared by elemental powder reactive synthesis

Porous Ni-Cr-Al alloy samples were fabricated by pressureless sintering of Ni, Cr, and Al elemental powders. The phase transformation, swelling behavior, pore structure parameters, microstructure, and pore formation mechanisms of porous Ni-Cr-Al alloys were systematically investigated. Results show that obvious swelling behavior occurs during sintering. The open porosity of the Ni-Cr-Al alloy increases as the sintering temperature increases below 920 C, followed by a relatively declining value for phase transformation beyond 920 C. The porous Ni-Cr-Al alloy samples exhibit an open porosity of 35.02% when sintered at 1200 C for 3 h. The main pore formation mechanisms are the Kirkendall effect and the development of interparticle pores.