Mechanical properties of oxidation-resistant Ni-Cr foams

Reticulated nickel foams were alloyed with chromium by pack-chromizing, resulting in Ni-Cr foams with 9-32 wt.% Cr and 2.6-3.5% relative density. The oxidation resistance at 1000 °C of the Ni-Cr foams and the corresponding bulk Ni-Cr alloys is the same, provided the foam's higher surface area is taken into account. The foam compressive yield stress at ambient temperature is in agreement with model predictions. The foam creep behavior, measured between 725 and 825 °C in the stress range of 0.1-0.2 MPa, is compared to two models assuming strut compression or strut bending as creep deformation modes. These models, which originally consider dislocation creep as the sole deformation mechanism, are modified to incorporate diffusional creep, due to the relatively fine grain size of the Ni-Cr struts. Good agreement is then found between data and the strut creep compression model.