--- title: What’s Mu Metal? | daily.dev description: Mu metal is a soft magnetic nickel-iron alloy (roughly 80% nickel, 15% iron, plus molybdenum) prized for its extremely high magnetic permeability, which... canonical: https://daily.dev/posts/what-s-mu-metal--bjdcyvrwv twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: What’s Mu Metal? | daily.dev og:description: Mu metal is a soft magnetic nickel-iron alloy (roughly 80% nickel, 15% iron, plus molybdenum) prized for its extremely high magnetic permeability, which... og:url: https://daily.dev/posts/what-s-mu-metal--bjdcyvrwv og:image: https://api.daily.dev/og/posts/BjDcYVRwV.png og:image:alt: What’s Mu Metal? og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # What’s Mu Metal? **[Hackaday](https://daily.dev/sources/hackaday)** · 4 min read · 0 upvotes · 0 comments ## Summary Mu metal is a soft magnetic nickel-iron alloy (roughly 80% nickel, 15% iron, plus molybdenum) prized for its extremely high magnetic permeability, which redirects magnetic flux around sensitive components rather than blocking it outright like an RF shield. It excels at shielding DC and low-frequency fields and has long been used in CRTs, tape heads, transformers, and photomultipliers, and remains relevant today in magnetometers, electron microscopes, and quantum/cryogenic instrumentation. The material is fragile to work with: bending, stamping, or welding degrades its properties unless it's hydrogen annealed afterward, and it saturates at a relatively low 0.75 tesla, requiring pairing with higher-saturation materials near strong magnets. Historically, mu metal was patented in 1923 by Willoughby S. Smith and Henry J. Garnett to compete with Western Electric's permalloy in transatlantic telegraph cable insulation. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is mu metal and how does it shield against magnetic fields? Mu metal is a soft magnetic nickel-iron alloy, typically about 80% nickel and 15% iron with molybdenum, known for extremely high magnetic permeability often around 100,000 or more. Rather than blocking magnetic fields like a conductive RF shield, it gives magnetic flux a lower-reluctance path around the protected object, making it especially effective against DC and low-frequency fields. _daily.dev surfaces engineering explainers like this for developers building hardware-adjacent or embedded systems._ ### Why does bending or welding mu metal ruin its shielding performance? Mu metal derives most of its high permeability from a specific metallurgical structure, so machining, stamping, welding, or bending introduces mechanical stress that seriously degrades its magnetic properties. High-performance shields are typically formed into shape first and then hydrogen annealed afterward to restore the permeability lost during fabrication. _engineers weighing shielding materials can track practical gotchas like this through daily.dev._ ### What is the saturation limit of mu metal and why does it matter for shield design? Mu metal has a saturation induction of only around 0.75 tesla, meaning it performs poorly closest to powerful magnets even though it excels with weak fields. Manufacturers recommend pairing it with a lower-permeability, higher-saturation material as an outer layer to tame strong fields before the mu metal handles the residual weaker field. _anyone designing shielding stacks can keep track of material trade-offs like this via daily.dev._ ## Similar posts on daily.dev - [MIT engineers develop a magnetic transistor for more energy-efficient electronics](https://daily.dev/posts/mit-engineers-develop-a-magnetic-transistor-for-more-energy-efficient-electronics-pyjp8liot) · MIT News · 0 upvotes · 0 comments - [Boston Metal gets a $75 million lifeline to produce critical metals](https://daily.dev/posts/boston-metal-gets-a-75-million-lifeline-to-produce-critical-metals-3lwg7tp9h) · MIT Technology Review · 0 upvotes · 0 comments - [TU Wien Researchers Find Entanglement in ‘Strange’ Metal](https://daily.dev/posts/tu-wien-researchers-find-entanglement-in-strange-metal-coyrykncr) · The Quantum Insider · 0 upvotes · 0 comments - [Neutron detector mobilizes muons for nuclear, quantum material](https://daily.dev/posts/neutron-detector-mobilizes-muons-for-nuclear-quantum-material-ru1ct6bzc) · Phys.org · 0 upvotes · 0 comments - [New Tantalum Process Could Ease Manufacturing of Superconducting Quantum Chips](https://daily.dev/posts/new-tantalum-process-could-ease-manufacturing-of-superconducting-quantum-chips-q4sfn6mba) · The Quantum Insider · 0 upvotes · 0 comments --- Tags: [#science](https://daily.dev/tags/science) [View this post on daily.dev](https://daily.dev/posts/what-s-mu-metal--bjdcyvrwv) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"What’s Mu Metal?","url":"https://daily.dev/posts/what-s-mu-metal--bjdcyvrwv","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/what-s-mu-metal--bjdcyvrwv"},"datePublished":"2026-08-31T14:23:00.806Z","dateModified":"2026-08-31T14:23:27.551Z","description":"Mu metal is a soft magnetic nickel-iron alloy (roughly 80% nickel, 15% iron, plus molybdenum) prized for its extremely high magnetic permeability, which...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/f528fd4f95d28e07e81a2ff42be0183e?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/f528fd4f95d28e07e81a2ff42be0183e?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Hackaday","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Hackaday","logo":"https://media.daily.dev/image/upload/s--JhDfhy70--/f_auto,q_auto/v1767541814/logos/hackaday","url":"https://daily.dev/sources/hackaday"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/what-s-mu-metal--bjdcyvrwv","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"science","timeRequired":"PT4M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Hackaday","item":"https://daily.dev/sources/hackaday"},{"@type":"ListItem","position":3,"name":"What’s Mu Metal?"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/what-s-mu-metal--bjdcyvrwv#faq","mainEntity":[{"@type":"Question","name":"What is mu metal and how does it shield against magnetic fields?","acceptedAnswer":{"@type":"Answer","text":"Mu metal is a soft magnetic nickel-iron alloy, typically about 80% nickel and 15% iron with molybdenum, known for extremely high magnetic permeability often around 100,000 or more. 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