Interaction of H2O and O-2 with Ni3Fe and their effects on ductility

Possible reasons for the high ductility of Ni3Fe and its insensitivity towa rd the testing environment have been investigated. Thermal desorption exper iments have shown that water dissociates on clean Ni3Fe surfaces to produce atomic hydrogen. Ductility measurements of cast and cold-rolled polycrysta lline Ni3Fe demonstrated that the reduced ductility was obtained only when the testing was performed with oxygen carefully removed. X-ray photoemissio n studies indicate that oxygen interacts with water to form hydroxyls, ther eby suppressing the production of atomic hydrogen. Hydrogen desorption from the Ni3Fe surface requires a lower activation energy, resulting in a small er surface hydrogen concentration at a given temperature. Hence it is possi ble that there is insufficient hydrogen to cause the nucleation and growth of brittle cracks for severe embrittlement. (C) 2000 Elsevier Science Ltd. All rights reserved.