Science Current Events | Science News |

How to make metal alloys that stand up to hydrogen

March 30, 2016

CAMBRIDGE, MA -- High-tech metal alloys are widely used in important materials such as the cladding that protects the fuel inside a nuclear reactor. But even the best alloys degrade over time, victims of a reactor's high temperatures, radiation, and hydrogen-rich environment. Now, a team of MIT researchers has found a way of greatly reducing the damaging effects these metals suffer from exposure to hydrogen.

The team's analysis focused on zirconium alloys, which are widely used in the nuclear industry, but the basic principles they found could apply to many metallic alloys used in other energy systems and infrastructure applications, the researchers say. The findings appear in the journal Physical Review Applied, in a paper by MIT Associate Professor Bilge Yildiz, postdoc Mostafa Youssef, and graduate student Ming Yang.

Hydrogen, which is released when water molecules from a reactor's coolant break apart, can enter the metal and react with it. This leads to a reduction in the metal's ductility, or its ability to sustain a mechanical load before fracturing. That in turn can lead to premature cracking and failure. In nuclear power plants, "the mechanical integrity of that cladding is extremely important," Yildiz says, so finding ways to improve its longevity is a high priority.

But it turns out that the initial entry of the hydrogen atoms into the metal depends crucially on the characteristics of a layer that forms on the metal's surface.

A coating of zirconium oxide naturally forms on the surface of the zirconium in high-temperature water, and it acts as a kind of protective barrier. If carefully engineered, this layer of oxide could inhibit hydrogen from getting into the crystal structure of the metal. Or, under other conditions, it could emit the hydrogen in gas form.

While researchers have been studying hydrogen embrittlement for decades, Yildiz says, "almost all of the work has been on what happens to hydrogen inside the metal: What are the consequences, where does it go, how does it lead to embrittlement? And we learned a lot from those studies." But there had been very little work on how hydrogen gets inside in the first place, she says. How hydrogen can enter through this surface oxide layer, or how it can be discharged as a gas from that layer, has not been quantified.

"If we know how it enters or how it can be discharged or ejected from the surface, that gives us the ability to predict surface modifications that can reduce the rate of entry," Yildiz says. Her team has found that it's possible to do just that, improving the barrier's ability to block incoming hydrogen, potentially by as much as a thousandfold.

The hydrogen has to first dissolve in the oxide layer before penetrating into the bulk of the metal beneath. But the hydrogen's dissolution can be controlled by doping that layer -- that is, by introducing atoms of another element or elements into it. The team found that the amount of hydrogen solubility in the oxide follows a valley-shaped curve, depending on the doping element's ability to introduce electrons into the oxide layer.

"There is a certain type of doping element that minimizes hydrogen's ability to penetrate, whereas other doping elements can introduce a maximum amount of electrons in the oxide, and facilitate the ejection of hydrogen gas right at the surface of the oxide," says Mostafa. So being able to predict the dopants that belong to each type is the essential trick to making an effective barrier.

The team's findings suggest two potential strategies, one aimed at minimizing hydrogen penetration and one at maximizing the ejection of hydrogen atoms that do get in.

The blocking strategy is "to target the bottom of the valley" by incorporating the right amount of an element, such as chromium, that produces this effect. The other strategy is based on different elements, including niobium, that propel hydrogen out of the oxide surface and protect the underlying zirconium alloy.

The doping could be accomplished by incorporating a small amount of the dopant metal into the initial zirconium alloy matrix, so that this in turn gets incorporated into the oxidation layer that naturally forms on the metal, the team says.

The team stresses that what they found is likely to be a general approach that can be applied to all kinds of alloys that form oxidation layers on their surfaces, as most do. Their approach could lead to improvements in longevity for alloys used in fossil fuel plants, bridges, pipelines, fuel cells, and many other applications.

"Any place you have metals exposed to high temperatures and water," Yildiz says -- for example on equipment used in oil and gas extraction -- is a potential situation where this work might be applicable.


The work was supported by the Consortium for Advanced Simulation of Light Water Reactors, funded by the U.S. Department of Energy, and computational support was provided by the U.S. National Science Foundation.

Massachusetts Institute of Technology

Related Metal Alloys Current Events and Metal Alloys News Articles

New metallic glass bounces
Engineers have created a new material with an unusual chemical structure that makes it incredibly hard and yet elastic.

Redefining temperature with precision lasers
A team of Australian scientists has produced a precision laser device that creates an accurate international standard for temperature.

Inkjet-printed liquid metal could bring wearable tech, soft robotics
New research shows how inkjet-printing technology can be used to mass-produce electronic circuits made of liquid-metal alloys for "soft robots" and flexible electronics.

Unusual skin cancer linked to chronic allergy from metal orthopedic implant
In rare cases, patients with allergies to metals develop persistent skin rashes after metal devices are implanted near the skin.

On the Road to Artificial Photosynthesis
The excessive atmospheric carbon dioxide that is driving global climate change could be harnessed into a renewable energy technology that would be a win for both the environment and the economy.

Newly Identified 'Universal' Property of Metamagnets May Lead to Everyday Uses
A new physics discovery made by a University of Virginia-led team may lead to more efficient refrigerators, heat pumps and airport scanners, among many possible uses -perhaps within a decade.

Biomedical applications of shape-memory polymers: How practically useful are they?
Polymers that exhibit shape-memory effect (SME) are an important class of materials in medicine, especially for minimally invasive deployment of devices.

Glasses strong as steel: A fast way to find the best
Scientists at Yale University have devised a dramatically faster way of identifying and characterizing complex alloys known as bulk metallic glasses (BMGs), a versatile type of pliable glass that's stronger than steel.

Can material rivaling graphene be mined out of rocks? Yes, if...
Will one-atom-thick layers of molybdenum disulfide, a compound that occurs naturally in rocks, prove to be better than graphene for electronic applications?

Silk-based surgical implants could offer a better way to repair broken bones
When a person suffers a broken bone, treatment calls for the surgeon to insert screws and plates to help bond the broken sections and enable the fracture to heal. These "fixation devices" are usually made of metal alloys.
More Metal Alloys Current Events and Metal Alloys News Articles

Metals and Alloys in the Unified Numbering System (UNS): 12th Edition DS56K

Metals and Alloys in the Unified Numbering System (UNS): 12th Edition DS56K
by ASTM International (Author)

The UNS for Metals and Alloys provides a means of correlating many internationally used metal and alloy numbering systems administered by societies, trade associations, and individual users and producers of metals and alloys. Jointly developed by ASTM International and the Society of Automotive Engineers (SAE), it provides the uniformity necessary for efficient indexing, record keeping, data storage and retrieval, and cross-referencing. The 12th edition has been updated to include more than 5,600 designations, 4,100 representative specification cross references, and 15,350 trade names. This edition includes:

Index to UNS Designations by Base Elements

Listing of UNS Numbers assigned-to date, with a description of each material covered and references to...

Phase Transformations in Metals and Alloys, Third Edition (Revised Reprint)

Phase Transformations in Metals and Alloys, Third Edition (Revised Reprint)
by David A. Porter (Author), Kenneth E. Easterling (Author), Mohamed Sherif (Author)

Expanded and revised to cover developments in the field over the past 17 years, and now reprinted to correct errors in the prior printing, Phase Transformation in Metals and Alloys, Third Edition provides information and examples that better illustrate the engineering relevance of this topic. It supplies a comprehensive overview of specific types of phase transformations, supplemented by practical case studies of engineering alloys. New in the Third Edition: Computer-aided calculation of phase diagrams Recent developments in metallic glasses The Scheil method of calculating a CCT diagram from a TTT diagram Expanded treatment of the nucleation and growth of polygonal ferrite and bainite New case studies covering copper precipitation hardening of very low carbon bainitic steel and very...

Phase Transformations in Metals and Alloys

Phase Transformations in Metals and Alloys
by David A. Porter (Author), K. E. Easterling (Author)

This text on phase transformations is for final year undergraduate and postgraduate students of metallurgy, materials science or engineering materials. It should also be useful for researchers working in industrial materials laboratories. The book is effectively in two parts: chapters 1-3 contain the background material necessary for understanding phase transformations: thermodynamics, kinetics, diffusion theory and the structure and properties of interfaces. Chapters 4-6 deal with specific transformations: solidification, diffusional transformations in solids and diffusionless transformations. Case studies of engineering alloys are included to provide a link between theory and practical reality.

Fundamentals of Creep in Metals and Alloys, Third Edition

Fundamentals of Creep in Metals and Alloys, Third Edition
by Michael E. Kassner Ph.D. (Author)

Although the present edition of Fundamentals of Creep in Metals and Alloys remains broadly up to date for metals, there are a range of improvements and updates that are either desirable, or required, in order to ensure that the book continues to meet the needs of researchers and scholars in the general area of creep plasticity. Besides updating the areas currently covered in the second edition with recent advances, the third edition will broaden its scope beyond metals and alloys to include ceramics, covalent solids, minerals and polymers, thus addressing the fundamentals of creep in all basic classes of materials.Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materialsTransmission electron micrographs provide direct...

Metals and Alloys in the Unified Numbering System

Metals and Alloys in the Unified Numbering System
by Society of Automotive Engineers (Author)

Metalwork in Early America: Copper and Its Alloys from the Winterthur Collection

Metalwork in Early America: Copper and Its Alloys from the Winterthur Collection
by Donald L. Fennimore (Author), Du Pont Winterthur Museum (Author), George J. Fistrovich (Photographer)

Copper and its alloys were an integral part of Americans' lives from the time of earliest settlement. Using the extensive collection at Winterthur as examples, Fennimore explores the importance of these metal for early Americans. A broad cross section of objects is included and linked to extensive manuscript and early published sources on both sides of the Atlantic. The book is organized into three parts: essays, color plates, and catalogue entries. The first three chapters cover mining and manufacturing techniques, the vast marketing network through which raw materials, and finished goods moved, and the factors that governed the marking of metal by their makers. These essays, followed by color plates, provide a background and introduce the entries that illustrate and discuss more than...

Guniter Fidget Spinner Toys, Aluminum alloy, for Relieving Stress, Continue to Spin for up to 2 to 3 minutes for Kids and Aduits (Cir-Black)

Guniter Fidget Spinner Toys, Aluminum alloy, for Relieving Stress, Continue to Spin for up to 2 to 3 minutes for Kids and Aduits (Cir-Black)
by Guniter (Publisher)

Inspire your inner-genius. The Spinner can help you find new perspectives as you put your brain to use, whether studying, brainstorming, researching. No matter where you can use it, without the restrictions of time and place. It can train our agility and flexibility in reaction to sudden problems.

Excellent and Helpful Toy. It is very helpful for kids to improve their attention. It is not only a children's toys, can also help people with Attention Deficit Disorder or ADHD. What's more, we can play it with our children, so that we have more happy time get along with them.

Portable. You can put it in your pocket. Just enjoy some fun play time by unleashing your helpful pocket .Eliminate stress and enjoy the occasional pass-time spin fun.


Oxidation of Metals and Alloys

Oxidation of Metals and Alloys
by o kubaschewski (Author)

Interfacial Phenomena in Metals and Alloys

Interfacial Phenomena in Metals and Alloys
by Lawrence E. Murr (Author)

U Uranium: Supplement Volume B2 Alloys of Uranium with Alkali Metals, Alkaline Earths, and Elements of Main Groups III and IV (Gmelin Handbook of Inorganic and Organometallic Chemistry - 8th edition)

U Uranium: Supplement Volume B2 Alloys of Uranium with Alkali Metals, Alkaline Earths, and Elements of Main Groups III and IV (Gmelin Handbook of Inorganic and Organometallic Chemistry - 8th edition)
by Hans U. Borgstedt (Author), Horst Wedemeyer (Author), Karl-Christian Buschbeck (Editor), Cornelius Keller (Editor)

Alloys of Uranium with Alkali Metals, Alkaline Earths, and Elements of Main Groups III and IV. The description of uranium and its compounds, for which the Gmelin Institute has started a series of volumes supplementing the main volume of 1936, follows in its arrangement closely the order chosen for the transuranium volumes. Part A treats "The Element", Part B "The Metal and its Alloys", Part C "The Compounds", Part D "The Chemistry in Solution", and finally Part E "The Coordination Compounds". Part E, "The Coordination Compounds" comprises two volumes which already have been finished and are available - completely written in English. Series A comprises 7 volumes which are all available. Series C will comprise 14 volumes of which only volume 6 is missing. Series D consists of 4 volumes...

© 2017