[Vo]:A possible role for hydrogen-induced lattice migration in alloy materials processing

[Roarty, Francis X]

  *   Department of Chemistry, Burlington, VT 05405, USA
  *   Title: A possible role for hydrogen-induced lattice migration in alloy 
materials processing

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Abstract

Evidence for hydrogen-induced lattice migration leading to rearranged lattices 
is given based on recent studies of palladium-rich alloys. In f.c.c. initially 
homogeneous PdRh, PdNi and PdPt alloys, hydrogen heat treatment (HHT) causes 
segregation. In PdRh alloys the segregation is clearly due to the miscibility 
gap which exists in this system; it takes place at both low hydrogen contents 
and high temperatures, approximately 873 K, and at moderate temperatures, 
approximately 473 K, and relatively high hydrogen contents. In the PdNi and 
PdPt alloys, however, segregation from HHT takes place only at moderate 
temperatures and relatively high hydrogen contents. In PdNi alloys it is shown 
that HHT at elevated temperatures promotes metal atom diffusion leading to the 
elimination of compositional variations in an initially inhomogeneous alloy. 
Dissolved hydrogen plays a dual role in some of these alloys, i.e. it catalyzes 
metal atom diffusion and also affects the equilibrium state.