Selective dissolution in AlFeNb alloys

Three different AlFeNb alloys of various compositions were prepared by arc melting. X‐ray diffraction (XRD) investigation of the melted samples proved the presence of two phases identified as a bcc α(Fe,Al) solid solution and a hexagonal C14 (Fe,Al)2Nb Laves phase. Subsequent electrochemical treatment allowed for a selective dealloying of the α(Fe,Al) or respective FeAl phase and resulted in releasing differently microstructured surfaces. These structures ranged from regular lamellar structures towards branched, fibrous structures. Scanning electron microscope (SEM) characterisation along with a local energy dispersive X‐ray spectroscopic (EDX) analysis of the samples and atomic absorption spectrometry (AAS) analysis of the electrolyte revealed a preferential Fe dissolution and the passive nature of the Nb. The results demonstrate that the phases present in the alloys strongly depend on the production and heat treatment history of the sample.

[1]  A. W. Hassel,et al.  Preparation and specific properties of single crystalline metallic nanowires , 2010 .

[2]  O. Prymak,et al.  Solidification and High-Temperature Phase Equilibria in the Fe–Al-rich Part of the Fe–Al–Nb System , 2010 .

[3]  M. Palm.  Phase equilibria in the Fe corner of the Fe–Al–Nb system between 800 and 1150 °C , 2009 .

[4]  A. W. Hassel,et al.  Spatial features control of self‐organised tungsten nanowire arrays , 2009 .

[5]  S. Milenkovic,et al.  Microstructure and mechanical properties of directionally solidified Fe–Al–Nb eutectic , 2008 .

[6]  Myung-Shin Lee,et al.  High strength ultrafine eutectic Fe–Nb–Al composites with enhanced plasticity , 2008 .

[7]  A. W. Hassel,et al.  Yield stress of monocrystalline rhenium nanowires , 2007 .

[8]  A. W. Hassel,et al.  Effect of the growth conditions on the spatial features of Re nanowires produced by directional solidification. , 2006, Nano letters.

[9]  M. Palm.  Concepts derived from phase diagram studies for the strengthening of Fe–Al-based alloys , 2005 .

[10]  I. Wright,et al.  Influence of Aluminum Depletion Effects on the Calculation of the Oxidation Lifetimes of FeCrAl Alloys , 2004 .

[11]  L. Singheiser,et al.  Growth Rates of Alumina Scales on Fe–Cr–Al Alloys , 2004 .

[12]  A. Bahadur.  Enhancement of high temperature strength and room temperature ductility of iron aluminides by alloying , 2003 .

[13]  D. Landolt,et al.  Passive films on stainless steels—chemistry, structure and growth , 2003 .

[14]  A. W. Hassel,et al.  Breakdown of ultrathin anodic valve metal oxide films in metal-insulator- metal-contacts compared with metal-insulator-electrolyte contacts , 2002 .

[15]  G. Tatlock,et al.  The Application of a Wedge-Shaped Sample Technique for the Study of Breakaway Oxidation in Fe–20Cr–5Al Base Alloys , 2000 .

[16]  H. Viefhaus,et al.  Segregation at the Al2O3-FeCrAl Interface During High-Temperature Oxidation , 1999 .

[17]  D. G. Morris,et al.  Strengthening at intermediate temperatures in iron aluminides , 1997 .

[18]  G. Effenberg,et al.  The Iron-Niobium Phase Diagram , 1993 .

[19]  P. Tortorelli,et al.  A review of recent developments in Fe_3Al-based alloys , 1991 .

[20]  M. Pourbaix.  Atlas of Electrochemical Equilibria in Aqueous Solutions , 1974 .

[21]  A. W. Hassel,et al.  Nanomechanics of single crystalline tungsten nanowires , 2008 .

[22]  D. G. Morris.  Possibilities for high-temperature strengthening in iron aluminides , 1998 .

[23]  Seetharama C. Deevi,et al.  Nickel and iron aluminides: an overview on properties, processing, and applications , 1996 .

[24]  K. Sieradzki,et al.  Validation of a percolation model for passivation of FeCr alloys: I current efficiency in the incompletely passivated state , 1988 .

[25]  Ortrud Kubaschewski,et al.  Iron-binary phase diagrams , 1982 .