Pitting corrosion of aluminum

This paper presents a survey of corrosion potentials, pitting potentials, and electrochemical characteristics for intermetallic particles commonly present in high-strength aluminum-based alloys. Results from relevant pure metals and solid solutions are also presented. It is seen that corrosion potentials and pitting potentials vary over a wide range for various intermetallics. Elaboration of the results reveals that the electrochemical behavior of intermetallics is more detailed than the simple noble or active classification based upon corrosion potential or estimated from the intermetallic composition. Intermetallics capable of sustaining the largest cathodic current densities are not necessarily those with the most noble Ecorr, similarly those with the least noble Ecorr will not necessarily sustain the largest anodic currents. The data herein was collected via the use of a microcapillary electrochemical cell facilitating electrode investigations upon intermetallic particles in the micrometer-squared range. This survey may be used as a tool for clarification of localized corrosion phenomena in Al alloys.

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Electrochemical Characteristics of Intermetallic Phases in Aluminum Alloys An Experimental Survey and Discussion

Electrochemical behavior and localized corrosion associated with Al7Cu2Fe particles in aluminum alloy 7075-T651

This paper presents results for corrosion potentials, pitting potentials, and electrochemical characteristics for intermetallic particles commonly present in high strength aluminum-based alloys, for tests conducted in a 01 M NaCl solution of varying pH via the use of a microcapillary electrochemical cell The intermetallics investigated were Mg2Si, MgZn2 ,A l7Cu2Fe, Al2Cu, Al2CuMg, and Al3Fe Elaboration of the results reveals that the electrochemical behavior of such compounds varies markedly with pH, with attendant ramifications for localized corrosion and protection in Al alloys Examples of this are shown for AA7075-T651, where it is shown that the localized corrosion morphology is drastically different upon the bulk alloy depending on the pH of the test environment A stochastic pitting is observed at an acid pH, near-neutral conditions result in a deterministic-type pitting, and a general corrosion is observed at an alkaline pH

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Investigation and Discussion of Characteristics for Intermetallic Phases Common to Aluminum Alloys as a Function of Solution pH

The role of precipitates enriched with copper on the susceptibility to pitting corrosion of the 2024 aluminium alloy

Electrochemical characteristics of the Al2Cu, Al3Ta and Al3Zr intermetallic phases and their relevancy to the localized corrosion of Al alloys

For years industrial polymer production has driven the development of rheological models to characterize the flow of materials. With the evolution of these models has come a corresponding advancement in the understanding of the complex mechanical properties. Recent efforts have been focused on modeling the behavior of complex fluids such as blood, whose microstructure leads to has simultaneous characteristics such as: thixotropy; elasticity; plasticity; and an evolving viscosity (part of which originates with the rouleaux’s evolution). The specific complex behavior of human blood can be analyzed via the analysis of Large-Amplitude-Oscillatory-Shear (LAOS) and Small-Amplitude-Oscillatory-Shear (SAOS) response tests. Unique features of human blood cannot be replicated in legacy steady-state models and, thus, have required the development of more comprehensive models capable of accurately fitting both steady state, transient flow and oscillatory shear flow. Expanding upon prior transient models, collaboration between the Chemical Engineering departments of the United States Military Academy and the University of Delaware has produced a new model, tensorial enhanced structural stress thixotropic-viscoelastic model (t-ESSTV). This model can capture the timescales contained within the plasma and individual red blood cells viscoelasticity and the thixotropic timescales associated with rouleaux breakdown and aggregation. The efficacy of t-ESSTV is demonstrated with a single Donor before consolidating the best fit model parameters of twelve Donor sets of rheological data. We then show the parametric correlations between model and physiological parameters and with the models’ prediction of microstructure, we correlate microstructure with the “elastic, solid-like” metrics as computed by Sequence of Physical Processes (SPP).

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Recent Advances in Biofluid Mechanics and Bio- and Hemorheology Collating Recent Advances in Predicting Complex Behavior of Human Blood With Thixo-Elasto-Visco-Plastic Models and Sequence of Physical Process

Polymer matrix based nano ferrite composites were prepared to achieve high inductance and hence to increase the performance of RF devices on chip inductors. A commercially suitable and scalable spin spray method was used to demonstrate the feasibility of deposition on silicon wafer. A detailed studies was performed with three alloys of Fe70Al5Cu5Si20Oδ, Co70Fe9Cu6Si15Oδ, and Co70Al5Fe20Si5Oδ compositions. These composites of ferrite magnetic nanomaterials were fabricated into the ring structures and properties such as permeability and resistivity were measured to correlated with morphology and concentration of the alloy in the matrix. Fabricated single coil coplanar inductors were characterized for the electrical and magnetic properties for the 100 to 100,000 KHz frequency range. The measurement showed performances improvement in the frequency range up to 1000KHz. The Co/Fe nanocomposite sample showed high permeability and a flat response as function of voltage and frequency making it a very good embedded inductor material. These composites provided inductance in the range up to 10 µH a suitable value for practical applications.

T.O. Knight

Papers

Electrochemical characteristics of the Al2Cu, Al3Ta and Al3Zr intermetallic phases and their relevancy to the localized corrosion of Al alloys

Recent Advances in Biofluid Mechanics and Bio- and Hemorheology Collating Recent Advances in Predicting Complex Behavior of Human Blood With Thixo-Elasto-Visco-Plastic Models and Sequence of Physical Process

Ferrites Embedded Nanocomposites for High-Q inductors