Freeze Casting is a Facile Method to Create Solid Solution Alloy Foams: Cu–Ni Alloy Foams via Freeze Casting

Abstract

Porous metals have attracted great attention for their functional and structural applications; however, they often possess limited applicability in their pure form for the areas requiring decent strength and corrosion resistance. In this study, pure copper (Cu), pure nickel (Ni), and Cu–Ni alloy foams with five different compositions are successfully fabricated using freeze casting, resulting in open-pore structures with varied porosity (from 55% to 75%). Their varied morphologies and crystal sizes are compared, and the lattice parameters and crystal sizes are calculated. The corrosion resistance of the synthesized Cu–Ni alloy foams is superior to those of the pure Cu and Ni foams. The weight loss rate of the Cu 7 Ni 3 alloy foam is six times and five times slower than those of the pure Ni and pure Cu foams in a sulfuric corrosive environment, respectively. The yield strength of Cu 7 Ni 3 alloy foam (53 ± 2% porosity) is 72 ± 2 MPa and its yield strength when normalized by the Gibson-Ashby model is the largest with a value of up to 852 ± 3 MPa. The elastic modulus and hardness values are varied in the range of 73.4–152.4 GPa and 1.6–4.7 GPa, respectively, depending on the composition of the alloy foam. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.