Crystallographic controlled dissolution and surface faceting in disordered face-centered cubic FePd

Electrochemical dissolution by congruent oxidation of Fe Pd in 1 M HCl solution was strongly controlled by crystallographic orientation. Anodic dissolution was characterized over a wide variety of grain surface plane orientations providing a detailed view of the crystallographic nature of oxidative dissolution and surface facet evolution as a function of grain orientation. Near {100}-oriented grains retained low surface roughness after corrosion and low dissolution rates. Grains with orientation within 2° of {111} were also topographically smooth after dissolution and were nearly as corrosion resistant as {100} grains. Overall dissolution depth depended linearly on crystallographic angle within 40° of {100} and within 10° of {111} planes. Post-corrosion surface faceting and dissolution were substantially increased at grain orientations near {110} and were highest between 10° and 20° from the {111} plane normal. Grains at these crystallographic angles roughened during oxidative dissolution by forming complex semi-periodic topographies. These finely spaced arrays of terraces and ledges likely consisted of combinations of more corrosion resistant low-index planes. Therefore, the overall corrosion depth within a grain possessing an initially irrational crystal orientation was determined by the amount of dissolution required to expose new, slowly dissolving surface facets with low-index orientations. Computations of Fe–Pd alloy surface energies and surface atom coordination as a function of crystal orientation are utilized to help support this explanation.

[1]  B. Holme,et al.  Preferential Grain Etching of AlMgSi(Zn) Model Alloys , 2010, ECS Transactions.

[2]  M. Baskes,et al.  The Role of Metallic Bonding in the Crystallographic Pitting of Magnesium , 2006, ECS Transactions.

[3]  H. Bunge.  Texture Analysis in Materials Science: Mathematical Methods , 2013 .

[4]  Christian G Elowsky,et al.  Bacterial Killing by Dry Metallic Copper Surfaces , 2010, Applied and Environmental Microbiology.

[5]  H. Konno,et al.  Anisotropic corrosion of iron in pH 1 sulphuric acid , 2010 .

[6]  G. Thompson,et al.  Influence of grain orientation on zinc enrichment and surface morphology of an AlZn alloy , 2010 .

[7]  S. Omanovic,et al.  The influence of crystallographic orientation distribution on 316LVM stainless steel pitting behavior , 2009 .

[8]  M. Lohrengel,et al.  Grain-dependent anodic dissolution of iron , 2007 .

[9]  G. Thompson,et al.  Crystallographic dissolution of high purity aluminium , 2007, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[10]  M. Lohrengel,et al.  Grain dependent electrochemical investigations on pure iron in acetate buffer pH 6.0 , 2006 .

[11]  Fei Ma,et al.  Calculation of the surface energy of fcc metals with modified embedded-atom method , 2004 .

[12]  S. Russo,et al.  “Exact” surface free energies of iron surfaces using a modified embedded atom method potential and λ integration , 2004 .

[13]  U. König,et al.  Microstructure of polycrystalline Ti and its microelectrochemical properties by means of electron-backscattering diffraction (EBSD) , 2001 .

[14]  P. Natishan,et al.  Metastable pitting behavior of aluminum single crystals , 2000 .

[15]  C. Breslin,et al.  Electrochemical studies on single-crystal aluminium surfaces , 1998 .

[16]  J. Howe.  Interfaces in Materials: Atomic Structure, Thermodynamics and Kinetics of Solid-Vapor, Solid-Liquid and Solid-Solid Interfaces , 1997 .

[17]  D. Tromans,et al.  Pitting Corrosion of Al and Al‐Cu Single Crystals , 1990 .

[18]  M. Sugiyama,et al.  Change in young's modulus of thermoelastic martensite Fe-Pd alloys , 1985 .

[19]  J. Heyraud,et al.  Equilibrium shape and temperature; Lead on graphite , 1983 .

[20]  R. Parsons,et al.  Specific Adsorption on Silver Single Crystals in Aqueous Solutions , 1978 .

[21]  M. Mclean.  Determination of the surface energy of copper as a function of crystallographic orientation and temperature , 1971 .

[22]  J. Nicholas.  Calculation of Surface Energy as a Function of Orientation for Cubic Crystals , 1968 .

[23]  M. Ives.  On kink kinetics in crystal dissolution , 1963 .

[24]  J. F. Nicholas,et al.  Bonds broken at atomically flat crystal surfaces—I , 1962 .