Morphological and Structural Transformations of Fe-Pd Powder Alloys Formed by Galvanic Replacement, Annealing and Acid Treatment

Abstract

In this article, we report the preparation and structural features of Fe-Pd powder alloys formed by galvanic replacement, annealing and selective dissolution of iron via acid treatment. The alloys were studied by the X-ray diffraction phase analysis, Mössbauer spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. The Fe@Pd core–shell particles were obtained by a galvanic replacement reaction occurring upon treatment of a body-centered cubic (bcc) iron powder by a solution containing PdCl42− ions. It was found that the shells are a face-centered cubic (fcc) Pd(Fe) solid solution. HCl acid treatment of the Fe@Pd core–shell particles resulted in the formation of hollow Pd-based particles, as the bcc phase was selectively dissolved from the cores. Annealing of the Fe@Pd core–shell particles at 800 °C led to the formation of fcc Fe-Pd solid solution. Acid treatment of the Fe-Pd alloys formed by annealing of the core–shell particles allowed selectively dissolving iron from the bcc Fe-based phase (Fe(Pd) solid solution), while the fcc Fe-rich Fe-Pd solid solution remained stable (resistant to acid corrosion). It was demonstrated that the phase composition and the Fe/Pd ratio in the alloys (phases) can be tailored by applying annealing and/or acid treatment to the as-synthesized Fe@Pd core–shell particles.

Preparation of Ni@Pd Core–Shell Nanoparticles Supported on KIT-6 by Ultrasound-Assisted Galvanic Replacement for Dodecahydro-N-ethylcarbazole Dehydrogenation

“…The use of surfactants and reducing agents is not in line with green chemistry and requires additional steps to remove them, which undoubtedly increases manufacturing costs. A method called the galvanic replacement reaction (GRR) to prepare bimetallic NPs of varying compositions and morphologies has attracted much attention from researchers in recent years. − It is a simple, versatile, and robust method to produce novel nanostructures. GRR is a thermodynamic spontaneous reaction initiated by the standard electrode potential difference between two metals.…”

Powder Metallurgy: Materials and Processing

“…The SI consists of 16 papers (published between 2022 and 2023): a review article [ 1 ], a viewpoint paper [ 2 ], a communication [ 3 ], and thirteen research articles [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. The papers reflect the current trends in the field: the search for new compositions (not investigated previously) of materials and the development of new processing approaches enabling better control and flexibility of the materials’ microstructures, shapes, and architectures.…”

“…The research papers report recent findings in metallic [ 4 , 5 , 6 , 7 , 8 , 9 ], ceramic [ 10 , 11 , 12 ], polymer [ 3 ], and composite materials [ 3 , 13 , 14 , 15 , 16 ].…”

“…The preparation of powders of metallic alloys has been addressed by Petrov et al [ 7 ] and Tikhov et al [ 9 ]. The fabrication of high-entropy alloys via powder metallurgy methods has been presented by Moser et al [ 5 ] and Batraev et al [ 6 ].…”