Intermetallic phases and element distribution in carbon-free PM high-speed steels of the Fe-Co-Mo type

In contrast to classical carbidic high-speed steels, carbon-free grades of the type Fe-Co-Mo(-W) obtain their strength by precipitation hardening through nm-size intermetallic µ phases; for example, (Fe,Co)7Mo6; coa­rser µ phases, in the low µm range, are required to prevent excessive grain growth d...

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Main Authors: Herbert Danninger, Elisabeth Eitenberger, Klaudia Hradil, Magdalena Dlapka
Format: Article
Language:English
Published: Taylor & Francis Group 2025-12-01
Series:European Journal of Materials
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Online Access:https://www.tandfonline.com/doi/10.1080/26889277.2025.2478107
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author Herbert Danninger
Elisabeth Eitenberger
Klaudia Hradil
Magdalena Dlapka
author_facet Herbert Danninger
Elisabeth Eitenberger
Klaudia Hradil
Magdalena Dlapka
author_sort Herbert Danninger
collection DOAJ
description In contrast to classical carbidic high-speed steels, carbon-free grades of the type Fe-Co-Mo(-W) obtain their strength by precipitation hardening through nm-size intermetallic µ phases; for example, (Fe,Co)7Mo6; coa­rser µ phases, in the low µm range, are required to prevent excessive grain growth during solution treatment. Precipitation hardening by intermetallic phases results in hardness >65 HRC combined with considerably higher temper resistance compared to carbides, which in turn results in improved cutting performance. On the other hand, the material is relatively soft as-quenched, <35 HRC, enabling machining and to some extent also cold working, and is hardened by an isothermal heat treatment without martensite formation, which strongly benefits geometrical precision. In this study, the intermetallic phases in the systems Fe-Mo, Co-Mo, and Fe-Co-Mo were investigated by pre­­paring specimens with varying composition from elemental powders through pressing and sintering. Metal­lographic sections were characterized by microscopy and SEM-EDX as well as X-ray diffraction. Compo­sition and crystallographic structure of the intermetallic phases were determined. It showed that the materials consist entirely of bcc matrix and µ phase; the ratio Fe:Co is almost the same in both phases and reflects the nominal one.
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spelling doaj-art-5d65f0e9fd0442e2a18e5c388721bc282025-08-20T03:05:42ZengTaylor & Francis GroupEuropean Journal of Materials2688-92772025-12-015110.1080/26889277.2025.2478107Intermetallic phases and element distribution in carbon-free PM high-speed steels of the Fe-Co-Mo typeHerbert Danninger0Elisabeth Eitenberger1Klaudia Hradil2Magdalena Dlapka3Institut für Chemische Technologien und Analytik, Technische Universität Wien, Wien/Vienna, AustriaInstitut für Chemische Technologien und Analytik, Technische Universität Wien, Wien/Vienna, AustriaX-ray Center, Technische Universität Wien, Wien/Vienna, AustriaInstitut für Chemische Technologien und Analytik, Technische Universität Wien, Wien/Vienna, AustriaIn contrast to classical carbidic high-speed steels, carbon-free grades of the type Fe-Co-Mo(-W) obtain their strength by precipitation hardening through nm-size intermetallic µ phases; for example, (Fe,Co)7Mo6; coa­rser µ phases, in the low µm range, are required to prevent excessive grain growth during solution treatment. Precipitation hardening by intermetallic phases results in hardness >65 HRC combined with considerably higher temper resistance compared to carbides, which in turn results in improved cutting performance. On the other hand, the material is relatively soft as-quenched, <35 HRC, enabling machining and to some extent also cold working, and is hardened by an isothermal heat treatment without martensite formation, which strongly benefits geometrical precision. In this study, the intermetallic phases in the systems Fe-Mo, Co-Mo, and Fe-Co-Mo were investigated by pre­­paring specimens with varying composition from elemental powders through pressing and sintering. Metal­lographic sections were characterized by microscopy and SEM-EDX as well as X-ray diffraction. Compo­sition and crystallographic structure of the intermetallic phases were determined. It showed that the materials consist entirely of bcc matrix and µ phase; the ratio Fe:Co is almost the same in both phases and reflects the nominal one.https://www.tandfonline.com/doi/10.1080/26889277.2025.2478107High speed steelsprecipitation hardeningintermetallic phasesphase analysis
spellingShingle Herbert Danninger
Elisabeth Eitenberger
Klaudia Hradil
Magdalena Dlapka
Intermetallic phases and element distribution in carbon-free PM high-speed steels of the Fe-Co-Mo type
European Journal of Materials
High speed steels
precipitation hardening
intermetallic phases
phase analysis
title Intermetallic phases and element distribution in carbon-free PM high-speed steels of the Fe-Co-Mo type
title_full Intermetallic phases and element distribution in carbon-free PM high-speed steels of the Fe-Co-Mo type
title_fullStr Intermetallic phases and element distribution in carbon-free PM high-speed steels of the Fe-Co-Mo type
title_full_unstemmed Intermetallic phases and element distribution in carbon-free PM high-speed steels of the Fe-Co-Mo type
title_short Intermetallic phases and element distribution in carbon-free PM high-speed steels of the Fe-Co-Mo type
title_sort intermetallic phases and element distribution in carbon free pm high speed steels of the fe co mo type
topic High speed steels
precipitation hardening
intermetallic phases
phase analysis
url https://www.tandfonline.com/doi/10.1080/26889277.2025.2478107
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