Study reveals clues to cause of hydrogen embrittlement in metals

Nov 19, 2012

Hydrogen, the lightest element, can easily dissolve and migrate within metals to make these otherwise ductile materials brittle and substantially more prone to failures.

Since the phenomenon was discovered in 1875, embrittlement has been a persistent problem for the design of structural materials in various industries, from battleships to aircraft and nuclear reactors. Despite decades of research, experts have yet to fully understand the physics underlying the problem or to develop a rigorous model for predicting when, where and how hydrogen embrittlement will occur. As a result, industrial designers must still resort to a trial- and-error approach.

Now, Jun Song, an Assistant Professor in Materials Engineering at McGill University, and Prof. William Curtin, Director of the Institute of Mechanical Engineering at Ecole Polytechnique Federale de Lausanne in Switzerland, have shown that the answer to hydrogen embrittlement may be rooted in how hydrogen modifies material behaviours at the nanoscale. In their study, published in , Song and Curtin present a new model that can accurately predict the occurrence of hydrogen embrittlement.

Under normal conditions, metals can undergo substantial plastic deformation when subjected to forces. This plasticity stems from the ability of nano- and micro-sized cracks to generate "dislocations" within the – movements of atoms that serve to relieve stress in the material.

"Dislocations can be viewed as vehicles to carry plastic deformation, while the nano- and micro-sized cracks can be viewed as hubs to dispatch those vehicles," Song explains. "The desirable properties of metals, such as ductility and toughness, rely on the hubs functioning well. Unfortunately those hubs also attract hydrogen atoms. The way hydrogen atoms embrittle metals is by causing a kind of traffic jam: they crowd around the hub and block all possible routes for vehicle dispatch. This eventually leads to the material breaking down."

State-of-the-art computer simulations were performed by Song to reveal explicitly how move within metals and how they interact with metal atoms. This simulation was followed by rigorous kinetic analysis, to link the nanoscale details with macroscopic experimental conditions.

This model has been applied to predict embrittlement thresholds in a variety of ferritic iron-based steels and produced excellent agreements with experiments. The findings provide a framework for interpreting experiments and designing next-generation embrittlement-resistant structural materials.

Explore further: Researchers make temporary, fundamental change to a material's properties

Related Stories

Hydrogen causes metal to break

Aug 11, 2010

Hydrogen is considered the fuel of the future. Yet this lightest of the chemical elements can embrittle the metals used in vehicle engineering. The result: components suddenly malfunction and break. A new special laboratory ...

In Brief: Unmasking elusive hydrogen

Jun 24, 2011

Researchers used the SEQUOIA inelastic spectrometer at the Spallation Neutron Source to map the dynamics of hydrogen atoms in a natural crystal of muscovite.

Model simulates atomic processes in nanomaterials

Mar 01, 2007

Researchers from MIT, Georgia Institute of Technology and Ohio State University have developed a new computer modeling approach to study how materials behave under stress at the atomic level, offering insights that could ...

The search for new materials for hydrogen storage

Sep 20, 2012

(Phys.org)—Hydrogen is the ideal fuel for new types of fuel cell vehicles, but one problem is how to store hydrogen. In his doctoral dissertation Serhiy Luzan studies new types of materials for hydrogen ...

Recommended for you

New complex oxides could advance memory devices

Sep 17, 2014

The quest for the ultimate memory device for computing may have just taken an encouraging step forward. Researchers at The City College of New York led by chemist Stephen O'Brien have discovered new complex ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Egleton
1 / 5 (1) Nov 20, 2012
What!?
We are willing to make definitive statements about Lattice Assisted Nuclear Reactions and yet we did not understand hydrogen embrittlement.
The astonishing arrogance of the hairless ape!