High-entropy alloy CoCrFeMnNi produced by powder metallurgy

ABSTRACT

Lately high-entropy alloys (HEAs) have been the topic of extensive research, as these materials are promising candidates for many challenging applications, as for example tools, moulds and functional coatings. In contrast to conventional alloys, HEAs consist of five or more principal elements, each having a concentration between 5 and 35 at.-%. Against expectations, HEAs show a rather simple microstructure consisting preferentially of cubic phases. Due to this microstructure, HEAs show promising properties, e.g. in terms of high-temperature stability, high strength and ductility. Within this research, a single-phase CoCrFeMnNi HEA was produced by powder metallurgy (PM). In contrast to conventional metallurgy, PM offers a lot of advantages, e.g. good material efficiency and high shape complexity. Gas atomised powder was used and selected PM methods are presented (e.g. pressureless sintering, spark plasma sintering, additive manufacturing (EBM)). The process methods were evaluated by characterising the material properties (density, microstructure, mechanical properties) of the compacted and sintered samples.

KEYWORDS:

• High-entropy alloy
• single phase
• powder metallurgy
• pressureless sintering
• spark plasma sintering
• gas atomisation
• selective electron beam melting
• dilatometry

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Nadine Eißmann studied Materials Science at the Technische Universität Dresden from October 2008 to March 2014. Since April 2014 she has been a PhD student at the Technische Universität Dresden; Institute of Materials Science.

Burghardt Klöden studied Physics at the Technische Universität Dresden and University of Sheffield from October 1996 to September 2002. From October 2002 to October 2006 he was a PhD student and obtained his PhD covering the topic of “severe plastic deformation by high-pressure torsion of NiAl” at the Technische Universität Dresden; Institute of Structural Physics. During the period from February 2006 to September 2016 he was a research fellow at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Branch Lab Dresden. Since September 2016 he has been group manager for “additive manufacturing – electron beam melting” at the Fraunhofer Institute for Manufacturing and Advanced Materials IFAM, Branch Lab Dresden.

Thomas Weißgärber studied Materials Science at the Technische Universität Dresden from September 1989 to July 1994. From August 1994 to July 1997 he was a PhD student at the Technische Universität Dresden; Institute of Materials Science and obtained his PhD covering the topic of “manufacturing, microstructure and properties of dispersions strengthened copper”. From August 1997 to June 1999 he was a research fellow at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Branch Lab Dresden. From July 1999 to March 2001 he was the group manager for “composite materials” at the Fraunhofer Institute for Manufacturing and Advanced Materials IFAM, Branch Lab Dresden. Since April 2001 he has been the Head of the Department of “Sintered and Composite Materials” at the Fraunhofer Institute for Manufacturing and Advanced Materials IFAM, Branch Lab Dresden. Since 2009 he is also the Deputy Director of Fraunhofer IFAM Dresden.

Bernd Kieback studied Physics from 1971 to 1976 at the State University Charkiw, Ukraine. From 1976 to 1982 he did his PhD in Materials Science at TU Dresden. During 1985–1990 he worked as the Head of the research group on hard materials composites, ZFW Dresden.

From 1987 to 1990 he was also Head of the Department of Tool Materials, ZFW Dresden. In 1991 he was Director of the Institute for Power Metallurgy and Composite Materials in the Institute for Solid State Physics and Materials Research Dresden (ZFW). From 1992 to the present he has been the Director of the Dresden Branch of the Fraunhofer Institute Manufacturing and Advanced Materials (IFAM). From 1993 to the present he has also been Full Professor (C4) and Head of the Chair Powder Metallurgy, Sintered and Composite Materials, TU Dresden. From 2008 to 2011 he was Director of the Institute for Materials Science (IfWW) TU Dresden.

ORCID

Burghardt Klöden http://orcid.org/0000-0003-1919-6894