Characterization and Modification of Microstructure in Al-Co-Cr-Fe-Ni Eutectic High-Entropy Alloys
A possible solution is found in the recently developed eutectic HEAs (EHEAs), which borrow the concept of using lamellar structures as in-situ composites to improve mechanical properties. The first such alloy, AlCoCrFeNi2.1, with an FCC+BCC lamellar microstructure remains as the most studied of EHEAs. Despite much work put into its characterization, much remains to be understood.
The first part of this work focuses on the as-cast microstructures of the eutectic and near-eutectic compositions of the AlCoCrFeNix system. Quantification of the phase volume and lamellar spacing is performed as a function of the Ni content. Orientation relationship and misorientation angle-axis changes in the five investigated alloys are also studied, with the previously unknown dependency of misorientation angle on the Ni content revealed.
The second part of this work studies the recrystallization process in the cold-rolled AlCoCrFeNi2.1 alloy. Development of the microstructure at various stages of recrystallization and the associated changes in mechanical properties are studied. Distinctive behavior of the two constituent phases during recrystallization, with varying rates of recrystallization and grain growth is observed. These findings show there is a possibility to further improve the EHEAs via careful thermo-mechanical processing.
Chalmers, Industri- och materialvetenskap, Material och tillverkning
Lozinko A., Mishin O. V., Yu T., Klement U., Guo S., Zhang Y., Quantification of microstructure in a eutectic high entropy alloy AlCoCrFeNi2.1, IOP Conf. Ser. Mater. Sci. Eng. 2019 (in print)
Lozinko A., Zhang Y., Mishin O. V., Klement U., Guo S., Microstructural characterization of eutectic and near-eutectic AlCoCrFeNi high-entropy alloys (submitted)
Lozinko A., Mishin O. V., Zhang Y., Klement U., Guo S., Effect of Recrystallization Fraction on Microstructure and Mechanical Property of AlCoCrFeNi2.1 Eutectic High-Entropy Alloy (manuscript)
Eutektiska högentropilegeringar : en lovande ny klass av högtemperaturlegeringar
Vetenskapsrådet (VR), 2016-01-01 -- 2020-12-31.
Metallurgi och metalliska material
Thesis for the degree of licentiate of engineering / Department of Materials Science and Engineering, Chalmers University of Technology: IMS-2019-19
Gamma/Delta, Hörsalsvägen 7A
Opponent: Asst. Prof. Ehsan Ghassemali, Jönköping University, Sweden