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

Abstract 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.