Synopsis: Doing a Crack Job on Aluminum

Atomic simulations of aluminum show how charge transfer from surface impurities can accelerate the growth of a crack tip.
Synopsis figure
R. J. Zamora et al., Phys. Rev. B (2012)

Engineers and materials scientists have long known that environmental factors can affect the fragility of manufactured components. Sometimes this is useful, as when a glassmaker applies a drop of water to a scribe mark to facilitate a clean break. More often, the chemical environment leads to reduced durability, as when aluminum under cyclic loading experiences a higher failure rate if the humidity increases. These effects are typically studied with a top-down approach: assemble lots of data on the way different materials respond to an environmental stress to arrive at a general mechanism. But a microscopic bottom-up approach is possible now with advanced computing tools, as Rick Zamora and colleagues at Cornell University, New York, report in Physical Review B.

The authors used the NASA Pleiades supercomputer to simulate the behavior of a crack in aluminum at an atomic level under different environmental conditions. These detailed multiscale calculations were run for three cases: a crack tip with no impurities, a crack tip with a single hydrogen atom, and a crack tip with a single oxygen atom. Zamora et al. ramped up the load on the simulated sample until a dislocation was created.

Results from these calculations predict that the hydrogen and oxygen impurities strenghen the aluminum bonds at the surface by means of charge transfer, inhibiting plasticity at the crack and raising the likelihood of brittle fracture. With this ab initio calculation, the Cornell team shows that a bottom-up approach can be a valuable tool for understanding embrittlement due to environmental causes. – David Voss


Features

More Features »

Announcements

More Announcements »

Subject Areas

Materials SciencePhysical Chemistry

Previous Synopsis

Quantum Information

Quantum Computers Have a Fit

Read More »

Next Synopsis

Particles and Fields

Narrowing the Range of Possibilities

Read More »

Related Articles

Viewpoint: How to Make Devices with Weyl Materials
Materials Science

Viewpoint: How to Make Devices with Weyl Materials

Weyl semimetals could be used to build a range of electronic devices, from superlenses for scanning tunneling microscopes to transistors. Read More »

Viewpoint: Relaxation is a Two-Step Process for Metallic Glasses
Materials Science

Viewpoint: Relaxation is a Two-Step Process for Metallic Glasses

Measurements of several metallic glasses under strain reveal that the materials relieve stress through a two-step process that has previously been seen only in “softer” glasses. Read More »

Synopsis: Protons in the Fast Lane
Energy Research

Synopsis: Protons in the Fast Lane

A proposed graphene-based material could offer speedy transport of protons without the need for water. Read More »

More Articles