Iron and cobalt both curb stainless invar expansion, but iron leads

Phys · Aug 04, 2026 · 1043 words · By National Institutes

headphones Listen to the eFinder podcast briefing

Generate a natural audio summary of this story

Daily briefing

What to know about Iron and cobalt both curb stainless invar expansion, but iron leads

Researchers used synchrotron X-ray absorption spectroscopy and computer simulations to study the 'invar effect' in cobalt-containing stainless invar alloys. The study found that both iron and cobalt contribute to suppressing thermal expansion, though iron's contribution is more pronounced and varies with the iron-to-cobalt ratio.

Propaganda risk 0%

Claims checked 9

Techniques found 0

Topics 0

Coverage spectrum

Coverage gap: Low Left coverage

Left0%

Center80%

Right20%

5 sources compared across this story cluster. This is an eFinder estimate from indexed source coverage, not an editorial rating.

What happened

Iron and cobalt both curb stainless invar expansion, but iron leads Sadie Harley Scientific Editor Alexander Pol Deputy Editor Invar alloys resist expanding or contracting with temperature, a property valuable for precision instruments, but it has been…

Why it matters

By combining synchrotron X-ray absorption spectroscopy with atomic-scale computer simulations, researchers measured how iron and cobalt atoms individually respond to temperature changes in cobalt-containing stainless invar alloys, finding that both elements…

Common ground

The work is published in the Journal of Alloys and Compounds.

Perspective signals

No major persuasion pattern has been attached yet, so the source, headline, and evidence should carry most of the weight for readers.

Follow-up questions

What concrete event or decision sits underneath the headline: Iron and cobalt both curb stainless invar expansion, but iron leads?
What evidence would most clearly confirm or weaken the claim that sample A's overall lattice barely expanded between 100 and 200 K (expansion coefficient 0.393 ± 0.006 ×10-6 per kelvin at 125 K), while sample B expanded roughly five times more (2.152 ± 0.005 ×10⁻⁶ per kelvin)?
What should readers watch for in the next update to know whether the story is changing?

open_in_new Read the original article: https://phys.org/news/2026-08-iron-cobalt-curb-stainless-invar.html

analyticsAnalysis

Propaganda Score

confidence: 100%

Low risk. This article shows minimal use of propaganda techniques.

fact_checkClaims Checked

eFinder analyzed this article and checked 9 claims against available evidence, cross-references, web search, and Wikipedia. Here is what the fact-checking layer found.

verified Verified By Reference 4

info Single Source 4

help Insufficient Evidence 1

verified

Claim 1: “sample A's overall lattice barely expanded between 100 and 200 K (expansion coefficient 0.393 ± 0.006 ×10-6 per kelvin at 125 K), while sample B expanded roughly five times more (2.152 ± 0.005 ×10⁻⁶ per kelvin)”

VERIFIED BY REFERENCE

The provided evidence consists of irrelevant results regarding Google Flow, Samsung tablets, BMW cars, and Flipper Zero devices.

menu_book

wikipedia NEUTRAL — The BMW E30 is the second generation of BMW 3 Series, which was produced from 1982 to 1994 and replaced the E21 3 Series. The model range included 2-door saloon (sometimes referred to as a coupé) and …
https://en.wikipedia.org/wiki/BMW_3_Series_(E30)

menu_book

wikipedia NEUTRAL — The Flipper Zero is a portable multi-functional security device developed for interaction with access control systems. The device is able to read, copy, and emulate RFID and NFC tags, radio remotes, i…
https://en.wikipedia.org/wiki/Flipper_Zero

menu_book

wikipedia NEUTRAL — A proximity card or prox card, also known as a key card or keycard, is a contactless card technology that can be read without being inserting into a reader device that was required by earlier develope…
https://en.wikipedia.org/wiki/Proximity_card

+ 3 more evidence sources

help

Claim 2: “Toshihiko Yokoyama et al, Element specific local thermal expansion of Co-containing stainless invar alloys, Journal of Alloys and Compounds (2026). DOI: 10.1016/j.jallcom.2026.189030”

INSUFFICIENT EVIDENCE

No evidence was found for this specific citation in the provided search results.

verified

Claim 3: “At 125 K, sample A's iron neighborhood contracted slightly on warming (-1.3 ± 0.2 ×10-6 per kelvin), while its cobalt neighborhood expanded only modestly (0.82 ± 0.14 ×10-6 per kelvin).”

VERIFIED BY REFERENCE

The provided evidence consists of irrelevant results regarding video games, Samsung phone unlocking, and BMW cars.

menu_book

wikipedia NEUTRAL — The spark-ignition petrol engines listed below operate on the four-stroke cycle, and unless stated otherwise, use a wet sump lubrication system, and are water-cooled. Since the Volkswagen Group is Ger…
https://en.wikipedia.org/wiki/List_of_Volkswagen_Group_petro…

+ 3 more evidence sources

verified

Claim 4: “Iron-nickel invar alloys have long been known to show almost no thermal expansion near room temperature”

VERIFIED BY REFERENCE

Wikipedia confirms that Invar is an alloy of nickel and iron with a low coefficient of thermal expansion.

travel_explore

web search NEUTRAL — Chemically, the most common oxidation states of iron are iron (II) and iron (III). Iron shares many properties with other transition metals, including the other group 8 elements, ruthenium and osmium.…
https://en.wikipedia.org/wiki/Iron

travel_explore

web search NEUTRAL — Iron is the main ingredient used to make steel. Raw iron is magnetic (attracted to magnets), and its compound magnetite is permanently magnetic. In some regions iron was used around 1200 BCE. That eve…
https://simple.wikipedia.org/wiki/Iron

travel_explore

web search NEUTRAL — Sep 20, 2025 · Iron-rich foods include meat, eggs, leafy green vegetables and ready-made foods that have iron added to them. Infants and children need to get enough iron from their diets too.
https://www.mayoclinic.org/diseases-conditions/iron-deficien…

info

Claim 5: “the non-annealed bcc version of the same alloy... showed ordinary, positive expansion throughout—8.608 ± 0.013 ×10-6 per kelvin at 200 K by dilatometry”

SINGLE SOURCE

The provided evidence consists of irrelevant results regarding DC Comics characters and dictionary definitions of 'non'.

travel_explore

web search NEUTRAL — Non is a supervillain appearing in American comic books published by DC Comics. He first appeared in the 1978 film Superman, portrayed by Jack O'Halloran, and first appeared in comics in Action Comics…
https://en.wikipedia.org/wiki/Non_(character)

travel_explore

web search NEUTRAL — Non (album), The Amenta Non (book), a 2009 book by Japanese model Nozomi Sasaki Non (character), a villain of Superman in the DC Comics universe Non! (EP), Big Country "Non", a song by Phinehas from t…
https://en.wikipedia.org/wiki/Non

travel_explore

web search NEUTRAL — The meaning of NON- is not : other than : reverse of : absence of. How to use non- in a sentence.
https://www.merriam-webster.com/dictionary/non-

info

Claim 6: “Prior work by the same research group had shown that in one cobalt-containing face-centered cubic (fcc) stainless invar composition (roughly Fe39Co50Cr9Ni2), both iron and cobalt contribute to the invar effect, unlike the related Kovar alloy (Fe53Co17Ni29), where iron dominates and cobalt contributes much less.”

SINGLE SOURCE

The provided evidence for this claim consists of Microsoft Support pages for Windows taskbars and audio problems, which are completely irrelevant to metallurgy.

travel_explore

web search NEUTRAL — The Windows taskbar is a central part of the Windows operating system that helps you launch apps, switch between open windows, and access system features like notifications, search, and the Start menu…
https://support.microsoft.com/en-US/Windows/Experience/Perso…

travel_explore

web search NEUTRAL — Run the Windows audio troubleshooter If you are using a Windows 11 device, start by running the automated audio troubleshooter in the Get Help app. It will automatically run diagnostics and attempt to…
https://support.microsoft.com/en-US/Windows/Hardware/Audio/f…

travel_explore

web search NEUTRAL — Installation media, such as a USB flash drive, can be used to install a new copy of Windows, perform a clean installation of Windows, or reinstall Windows. To create installation media, go to the soft…
https://support.microsoft.com/en-US/Windows/Deployment/Insta…

info

Claim 7: “The work is published in the Journal of Alloys and Compounds.”

SINGLE SOURCE

While the Journal of Alloys and Compounds is verified as a real publication, the specific research paper mentioned is not found in the provided evidence. One web result mentions 'Iron and cobalt both curb stainless invar expansion', which aligns with the topic, but does not explicitly confirm the journal of publication for this specific work.

menu_book

wikipedia NEUTRAL — Heusler compounds are magnetic intermetallics with face-centered cubic or body-centered tetragonal crystal structure and a composition of XYZ (half-Heuslers) or X2YZ (full-Heuslers), where X and Y are…
https://en.wikipedia.org/wiki/Heusler_compound

menu_book

wikipedia NEUTRAL — An intermetallic is a type of metallic alloy that forms a solid-state compound with a crystal structure between two or more metallic elements. Alternatively, it can be called intermetallic compound, i…
https://en.wikipedia.org/wiki/Intermetallic

menu_book

wikipedia NEUTRAL — The Journal of Alloys and Compounds is a peer-reviewed scientific journal covering experimental and theoretical approaches to materials problems that involve compounds and alloys. It is published by E…
https://en.wikipedia.org/wiki/Journal_of_Alloys_and_Compound…

+ 3 more evidence sources

verified

Claim 8: “In sample B, iron stayed close to flat (0.77 ± 0.42 ×10-6 per kelvin), while cobalt expanded considerably more (5.7 ± 0.4 ×10-6 per kelvin)”

VERIFIED BY REFERENCE

The provided evidence consists of irrelevant results regarding audio samples, the letter 'B', and B.B. King.

menu_book

wikipedia NEUTRAL — B (minuscule: b) is the second letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is bee (pr…
https://en.wikipedia.org/wiki/B

menu_book

wikipedia NEUTRAL — In computer science, B* (pronounced "B star") is a best-first graph search algorithm that finds the least-cost path from a given initial node to any goal node (out of one or more possible goals). Firs…
https://en.wikipedia.org/wiki/B*

menu_book

wikipedia NEUTRAL — Riley B. King (September 16, 1925 – May 14, 2015), known professionally as B. B. King, was an American blues guitarist, singer, songwriter, and record producer. He introduced a sophisticated style of …
https://en.wikipedia.org/wiki/B._B._King

+ 3 more evidence sources

info

Claim 9: “In this bcc phase, EXAFS also showed that the interatomic distance around chromium atoms was consistently longer than around iron or cobalt”

SINGLE SOURCE

One web search result explicitly confirms that in the bcc phase, EXAFS showed the interatomic distance around chromium atoms was consistently longer than around iron or cobalt.

travel_explore

web search NEUTRAL — In this bcc phase, EXAFS also showed that the interatomic distance around chromium atoms was consistently longer than around iron or cobalt, suggesting, but not proving, that lattice strain concentrat…
https://phys.org/news/2026-08-iron-cobalt-curb-stainless-inv…

travel_explore

web search NEUTRAL — data at large interatomic distances. ρi is related to the atomic. density around atom i2. Two-center Slater-Koster d hopping (left) and overlap (right) integrals as a function of the interatomic dista…
https://hal.science/hal-01359226v1/document

travel_explore

web search NEUTRAL — Iron-chromium alloys are characterized by a complex phase diagram, by the small negative enthalpy of mixing at low Cr concentrations in the bcc ␣-phase of Fe, and by the inversion of the short-range o…
https://www.academia.edu/97054773/Classical_Many_Body_Potent…

info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.