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oa Exploring Lattice Defects in Palladium and Its Alloys Using Dissolved Hydrogen
Part I: Hydrogen Solubility and Its Segregation to Dislocations and Vacancies
- Source: Platinum Metals Review, Volume 45, Issue 3, Jul 2001, p. 114 - 121
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- 01 Jan 2001
Abstract
The first part of this paper describes a combination of physical metallurgical techniques and hydrogen (H2) solubilities employed to help in the characterisation of defects in palladium and its alloys. Cold working or hydride formation and decomposition introduce large dislocation densities into palladium and palladium alloys. These can be examined by transmission electron microscopy and correlated with hydrogen (H) segregation to the stress fields of the dislocations determined from H2 solubilities. H atoms are strongly trapped by vacancies in the palladium lattice and evidence for vacancy trapping in cold-worked palladium is shown by deviations in H2 solubility, different to that expected if H segregated only to the dislocation stress fields. The second part of this paper, to be published in the October 2001 issue, will be concerned with hydrogen segregation to defects introduced by the internal oxidation of palladium alloys or by treatment at moderately high temperatures and hydrogen pressures.