Mechanical properties of composition modulated Cu-Ni foils

Measurements have been made of the Young's, flexural, and torsional moduli of compositionally modulated Cu-Ni foils. The average composition of the foils was 50-at. % Ni and the wavelength of the modulation ranged from 8 to 80 Å. At a wavelength of 20 Å, the flexural modulus exhibited a maximum and had a value two times greater than that measured at shorter or longer wavelengths or that calculated from the bulk single-crystal elastic constants of a homogeneous alloy. The Young's and torsion moduli exhibited two maxima at 12 and 28 Å. These results are consistent with earlier measurements of the biaxial modulus using a bulge tester. It was also observed that at a wavelength of 20 Å there was a threefold increase in the breaking stress of the foils as compared with homogeneous bulk alloys.