Fracture of amorphous Ni-Pd-P alloys

Abstract

Mechanical behaviour, deformation and fracture have been investigated for amorphous Ni-Pd-P alloys made by an improved Pond and Maddin method. The stress-strain curves of Ni₅₅Pd₃₅P₁₀ and Ni₆₃Pd₁₇P₂₀ show quasi-brittle behaviour with average fracture stresses of 149 and 142 kg/mm², respectively. These stresses are high in comparison with those of normal metals and alloys. The elongations are small, 0·042 and 0·023% for Ni₅₅Pd₃₅P₁₀ and Ni₆₃Pd₁₇P₂₀, respectively, as is the elongation of all amorphous alloys. Fracture surfaces observed with a scanning electron microscope show two distinct regions, a featureless zone and one called a ‘vein’ or ‘ridge’ pattern. A suggested grease model gives a good simulation of the actual fracture morphology.