reply to M. G. Smith

Austin, Diane J.

doi:10.1525/ae.1984.11.1.02a00130

Cited by 6 publications

(5 citation statements)

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“…The manganese content of the deposit varies from 7 to 30 w/o and increases with increasing MnC12. Contrary to reports in the literature (24), there is a dramatic dependence of alloy composition on potential, particularly at the higher MnC12 concentrations. At all concentrations, the manganese content of the deposit drops slightly at a critical potential.…”

Section: Resultscontrasting

confidence: 99%

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The Electrodeposition of an Aluminum‐Manganese Metallic Glass from Molten Salts

Stafford

1989

J. Electrochem. Soc.

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The electrodeposition of binary aluminum-manganese alloys from chloroaluminate molten salts is reported. The manganese content of the electrodeposit varies from 7 to 30 w/o and is dependent upon deposition potential and the relative concentrations of A12C17 and Mn++ in the melt. At small cathodic overpotentials the deposition process, with respect to alloy composition, is kinetically controlled. At larger cathodic overpotentials, it becomes mass transport limited in Mn + § and then A12C17-. The most uniform and brightest deposits are obtained at a constant potential of -0.3V with respect to an aluminum wire in the same electrolyte. The potential dependence of alloy composition allows one to create homogeneous, graded and modulated structures from a single electrolyte. The structure of the as-deposited alloy appears to be that of a metallic glass above 27 w/o manganese and a mixture of glass and supersaturated aluminum below 27 w/o. Heating to 400~ converts the deposit containing less than 26 w/o Mn to a mixture of the orthorhombic A16Mn intermetallic and aluminum. The ability to electrodeposit intermetallic compounds on a near atomic scale presents interesting possibilities for high temperature alloys.

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Section: Resultscontrasting

confidence: 99%

“…MnC12 (24,25). Specular deposits containing 16-45 weight percent (w/o) Mn have been obtained from molten salt electrolytes containing 0.4 w/o MnC12 at current densities as high as 100 mA/cm 2.…”

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confidence: 99%

The Electrodeposition of an Aluminum‐Manganese Metallic Glass from Molten Salts

Stafford

1989

J. Electrochem. Soc.

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“…As the current density is increased, the partial current for the reduction of the Zr species should reach a limiting value, whereas the partial current for the reduction of Al 2 Cl 7 Ϫ , which is present in this melt at a concentration of 3.24 M at 353 K, continues to increase. This behavior is a common feature of overpotential alloy deposition in chloroaluminate melts and was observed during the electrodeposition of Al-Cr 20,21 Al-Mn, 23,44 Al-Mo, 45 and Al-Ti. 24,25,39,46 The finding that plating solutions containing Zr͑IV͒ lead to alloys with higher Zr content than plating solutions containing equal concentrations of Zr͑II͒ may be reconciled by considering the diffusion coefficient data in Table I.…”

Section: Resultsmentioning

confidence: 66%

Electrodeposition of Al-Zr Alloys from Lewis Acidic Aluminum Chloride-1-Ethyl-3-methylimidazolium Chloride Melt

Tsuda

Hussey

Stafford

et al. 2004

J. Electrochem. Soc.

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The electrochemistry of Zr͑IV͒ and Zr͑II͒ and the electrodeposition of Al-Zr alloys were examined in the Lewis acidic 66.7-33.3 mol % aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt at 353 K. The electrochemical reduction of Zr͑IV͒ to Zr͑II͒ is complicated by the precipitation of ZrCl 3 ; however, solutions of Zr͑II͒ can be prepared by reducing Zr͑IV͒ with Al wire. Al-Zr alloys can be electrodeposited from plating baths containing either Zr͑IV͒ or Zr͑II͒, but for a given concentration and current density, baths containing Zr͑IV͒ lead to Al-Zr alloys with the higher Zr content. This result was traced to the diminutive concentration-dependent diffusion coefficient for Zr͑II͒. It was possible to prepare Al-Zr alloys containing up to ϳ17% atomic fraction ͑atom %͒ Zr. The structure of these deposits depended on the Zr content. Alloys containing less than 5 atom % Zr could be indexed to a disordered face-centered cubic structure similar to pure Al, whereas alloys containing ϳ17 atom % Zr were completely amorphous ͑metallic glass͒. The chloride pitting potentials of alloys with more than 8 atom % Zr were approximately ϩ0.3 V relative to pure Al.The maximum solubility of zirconium in face-centered cubic ͑fcc͒ aluminum is 0.08% atomic fraction ͑atom %͒. This occurs at the peritectic transformation point at 660.5°C. At room temperature, zirconium has negligible solubility in aluminum. 1 However like most aluminum-transition metal alloys, supersaturated solid solutions greatly exceeding the equilibrium solubility can be obtained by nonequilibrium processing methods. For example, solid solutions containing up to 3.0 atom % zirconium have been produced by rapid solidification 2-6 and vapor deposition. 7 The Al-Zr solid solution, although metastable, shows good thermal stability up to ϳ400-450°C. This observation is consistent with the general trend that the thermal stability of the solid solution is related to the melting point of the alloying addition; i.e., the higher the melting point, the more stable the solid solution. 8 The thermal decomposition of the supersaturated solid solution results in the nucleation of a metastable Al 3 Zr phase having an ordered cubic L1 2 structure (Cu 3 Au-type͒ 5,6,9-13 and eventually the equilibrium Al 3 Zr phase having a tetragonal structure. These two phases, cubic Al 3 Zr and tetragonal Al 3 Zr, have also been observed in supersaturated Al-Zr solid solutions produced by rapid quenching. 14 The properties of aluminum and its alloys are significantly altered by the addition of zirconium. The rapid solidification of binary Al-Zr alloys with more than 0.15 atom % zirconium produces considerable grain refinement, 15,16 resulting in aluminum grain sizes typically less than 10 m. The general explanation for this phenomenon is that L1 2 Al 3 Zr acts as a low-energy nucleation site for fcc Al due to the similar crystal structures. Rapid quenching is required to ensure that the Al 3 Zr solidifies with the metastable L1 2 structure rather than the equilibrium tetragonal structure...

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“…In the case of Al-Mn, alloy compositions approaching 50 a/o Mn have been reported in the literature, and several studies have examined the dependence of alloy composition on various deposition parameters such as current density, temperature, melt composition, and electrolyte flow (10)(11)(12)(13)(14)(15)(16)(17)(18). Although there is some discrepancy in the literature about the extent to which the potential or current density influences alloy composition, the overwhelming consensus is that alloy composition is directly related to the relative concentrations of Mn 2+ and Al 2 Cl 7 in the electrolyte.…”

Section: Resultsmentioning

confidence: 99%

The Structure of Electrodeposited Aluminum Alloys from Chloroaluminate Ionic Liquids: Let’s Not Ignore the Temperature

2014

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Electrodeposited alloys are rarely in thermodynamic equilibrium, and several unique microstructural features such as extended solid solubility, metastable crystalline phases, and metallic glasses are generally observed. Because the excess free energy of the deposit is inversely proportional to the atomic mobility, phase constitution depends strongly on deposition temperature. This paper examines the influence of deposition temperature on the crystal structure of electrodeposited Al-Mn and Al-Ti alloys electrodeposited from AlCl3-NaCl and AlCl3-EMImCl ionic liquids from temperatures ranging from 80 °C to 425 °C. Deposition at low temperature favors the preferential deposition of amorphous and crystalline phases which appear as high temperature variants in the equilibrium phase diagram. These structures generally have high symmetry, and for this reason are relatively easy to nucleate. The room temperature equilibrium phases, which generally have a more complicated structure, can only be obtained at elevated deposition temperatures.

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reply to M. G. Smith

Cited by 6 publications

References 0 publications

The Electrodeposition of an Aluminum‐Manganese Metallic Glass from Molten Salts

The Electrodeposition of an Aluminum‐Manganese Metallic Glass from Molten Salts

Electrodeposition of Al-Zr Alloys from Lewis Acidic Aluminum Chloride-1-Ethyl-3-methylimidazolium Chloride Melt

The Structure of Electrodeposited Aluminum Alloys from Chloroaluminate Ionic Liquids: Let’s Not Ignore the Temperature

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