Enhanced elastic modulus in composition modulated copper-nickel-iron foils

Abstract

Young’s modulus was measured by tensile testing on Cu/NiFe thin foils containing short-wavelength composition modulation of 1.4–10.0 nm. The foils, of 53% Cu/40% Ni-7% Fe composition, were produced by vapor deposition using a three-source evaporator. As compared with homogeneous foils of the same average composition, the modulated foils exhibited an appreciable increase (up to 300%) in modulus for two distinct ranges of composition wavelength: 2.1–2.7 and 3.6–4.1 nm. The increase was proportional to the square of the composition amplitude. The stress-strain curves of the modulated foils displayed a Hookean behavior below 0.2% strain.