Catastrophic oxidation and self-passivation of Mo-40wt.%Cu alloy

Catastrophic oxidation and self-passivation of Mo-40wt.%Cu alloy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Catastrophic oxidation and self-passivation of Mo-40wt.%Cu alloy Anton Klimashin, Valery V. Belousov, Sergey Shevtsov This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9564496/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 9 You are reading this latest preprint version Abstract The Mo-40wt.%Cu pseudo-alloy, prized for thermal conductivity and electrical performance, is used as heat sinks for high-density integrated circuits and power semiconductors, ultrahigh-voltage electric contact materials in heavy-duty switches, circuit breakers and electrodes, blocking materials in microwave packages, substrates for radar transistors and MEMS sensors. The oxidation behavior of the Mo-40wt.%Cu alloy was investigated at 450–550°C in air, revealing a two-stage process comprising initial catastrophic oxidation caused by a liquid phase formation in the oxide scale followed by self-passivation. Thermogravimetric analysis demonstrated parabolic kinetics during the catastrophic stage, governed by diffusion-controlled mechanisms, with parabolic rate constant increasing from 0.5·10⁻⁵ to 2.6·10⁻⁵ kg² m⁻⁴ s⁻¹ as temperature rose from 480 to 520°C (three orders of magnitude higher than the constant of pure copper oxidation 2.5·10⁻ 8 kg² m⁻⁴ s⁻¹ at 500°C). Subsequent passivation led to a marked reduction in oxidation rate, culminating in a mass-gain plateau. X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy elucidated the formation of a two-layered oxide scale: an inner layer of copper molybdates (CuMoO₄, Cu₃Mo₂O₉, Cu₃.₈₅Mo₃O₁₂, Cu₆Mo₅O₁₈) and an outer dense CuO layer after the passivation begins. This CuO layer upon achieving continuity, exhibiting low ionic conductivity, impedes both copper cation and oxygen anion diffusion, thereby arresting further oxidation. Unlike the MoO₃-deposit induced catastrophic oxidation of copper, this self-passivation mechanism in the Mo-40wt.%Cu alloy offers insights into designing a technology to protect pseudo-alloys from catastrophic oxidation. Self-passivation catastrophic oxidation pseudo-alloy. Full Text Additional Declarations No competing interests reported. Supplementary Files VideoS1.mov Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 14 May, 2026 Reviews received at journal 14 May, 2026 Reviews received at journal 13 May, 2026 Reviewers agreed at journal 07 May, 2026 Reviewers agreed at journal 07 May, 2026 Reviewers invited by journal 07 May, 2026 Editor assigned by journal 06 May, 2026 Submission checks completed at journal 06 May, 2026 First submitted to journal 29 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9564496","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":640174706,"identity":"310e9812-ff73-413e-a217-4a232a1a6d2d","order_by":0,"name":"Anton Klimashin","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5ElEQVRIiWNgGAWjYFACNsYDCUDKgJmB8QGQ5uEjQgsDTAuzAUgLG1FaQBRQOZsEhE8A8LcfSzjwMMfO3pyd91jl1xw7GTYG5oePbuDRInEm7cCBxG3JiTub+dJuy25LBjqMzdg4B581B9IbgFqYEwwO85jdltzGDNTCwyaNT4v8+ecgLfX2IC3FktvqCWsxuAF22GHGDUAtjB+3HSasxfDGswSgluOJQC3G0ozbjvOwMRPwi9z5NMOHP7dV2xucP2P4EcTgZ29++Biv95EBMw+YJFY5CDD+IEX1KBgFo2AUjBgAAF4/SZinkflFAAAAAElFTkSuQmCC","orcid":"","institution":"Baikov Institute of Metallurgy and Materials Science","correspondingAuthor":true,"prefix":"","firstName":"Anton","middleName":"","lastName":"Klimashin","suffix":""},{"id":640174707,"identity":"13a94285-87cf-47bc-a807-0a83dd793657","order_by":1,"name":"Valery V. 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The oxidation behavior of the Mo-40wt.%Cu alloy was investigated at 450\u0026ndash;550\u0026deg;C in air, revealing a two-stage process comprising initial catastrophic oxidation caused by a liquid phase formation in the oxide scale followed by self-passivation. Thermogravimetric analysis demonstrated parabolic kinetics during the catastrophic stage, governed by diffusion-controlled mechanisms, with parabolic rate constant increasing from 0.5\u0026middot;10⁻⁵ to 2.6\u0026middot;10⁻⁵ kg\u0026sup2; m⁻⁴ s⁻\u0026sup1; as temperature rose from 480 to 520\u0026deg;C (three orders of magnitude higher than the constant of pure copper oxidation 2.5\u0026middot;10⁻\u003csup\u003e8\u003c/sup\u003e kg\u0026sup2; m⁻⁴ s⁻\u0026sup1; at 500\u0026deg;C). Subsequent passivation led to a marked reduction in oxidation rate, culminating in a mass-gain plateau. X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy elucidated the formation of a two-layered oxide scale: an inner layer of copper molybdates (CuMoO₄, Cu₃Mo₂O₉, Cu₃.₈₅Mo₃O₁₂, Cu₆Mo₅O₁₈) and an outer dense CuO layer after the passivation begins. This CuO layer upon achieving continuity, exhibiting low ionic conductivity, impedes both copper cation and oxygen anion diffusion, thereby arresting further oxidation. Unlike the MoO₃-deposit induced catastrophic oxidation of copper, this self-passivation mechanism in the Mo-40wt.%Cu alloy offers insights into designing a technology to protect pseudo-alloys from catastrophic oxidation.\u003c/p\u003e","manuscriptTitle":"Catastrophic oxidation and self-passivation of Mo-40wt.%Cu alloy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-18 09:25:38","doi":"10.21203/rs.3.rs-9564496/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-14T08:29:24+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-14T07:10:25+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-13T09:23:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"84272985134230038224803206615151463223","date":"2026-05-07T05:32:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"161809981376708876169830030832981708898","date":"2026-05-07T05:17:52+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-05-07T05:17:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-06T11:37:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-05-06T11:37:11+00:00","index":"","fulltext":""},{"type":"submitted","content":"High Temperature Corrosion of Materials","date":"2026-04-29T10:23:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"high-temperature-corrosion-of-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [High Temperature Corrosion of Materials](https://www.springer.com/journal/11085)","snPcode":"11085","submissionUrl":"https://submission.nature.com/new-submission/11085/3","title":"High Temperature Corrosion of Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"bd34123e-9384-4b12-8bb9-3f23336907be","owner":[],"postedDate":"May 18th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-14T08:29:24+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-14T07:10:25+00:00","index":11,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-13T09:23:44+00:00","index":10,"fulltext":""},{"type":"reviewerAgreed","content":"84272985134230038224803206615151463223","date":"2026-05-07T05:32:02+00:00","index":9,"fulltext":""},{"type":"reviewerAgreed","content":"161809981376708876169830030832981708898","date":"2026-05-07T05:17:52+00:00","index":8,"fulltext":""},{"type":"reviewersInvited","content":"2","date":"2026-05-07T05:17:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-06T11:37:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-05-06T11:37:11+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-18T09:25:38+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-18 09:25:38","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9564496","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9564496","identity":"rs-9564496","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}