Simulations of the effects of hydrogen on the tensile properties of palladium

M. RUDA; E. CRESPO; S. RAMOS; E. BRINGA; F. BRASCHI; M.L. ALÍ

San Pablo

Conferencia; ABM - TMS Second Pan American Materials Conference; 2014

Asociación Brasilero de Materiales

The Pd-H system is of great technological interest in relation to H storage and purification applications, as well as catalysis. In this work molecular dynamics (MD) atomistic simulations of uniaxial tensile deformation have been performed on single crystal and nano-polycrystalline Pd samples at room temperature (300 K) with different concentrations of H. The polycrystalline samples consisted on columnar grains randomly oriented of average grain sizes ranging from 5-20 nm.  Interatomic potentials of the Embedded-Atom (EAM) type were used to describe the interactions among atoms.  The H absorption process was modeled at the atomistic scale by Monte Carlo simulations in the TPmuN ensemble. For mono-crystalline Pd in the alpha phase, stress-strain curves showed decreasing elastic moduli and yield strength with increasing H concentration. At low H concentrations in the polycrystalline samples, H agglomerated at grain boundaries, anchoring them and stopping the grain growth which would occur under tension in samples without H. At high H concentrations (beta phase) homogeneous hydride formation was observed