| 1. |
- Vida, Ádám, et al.
(författare)
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A Sequence of Phase Transformations and Phases in NiCoFeCrGa High Entropy Alloy
- 2021
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 14(5):1076
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Tidskriftsartikel (refereegranskat)abstract
- The present investigation is directed to phase transitions in the equimolar NiCoFeCrGa high entropy alloy, which is a mixture of face-centered cubic (FCC) and body-centered cubic (BCC) crystalline phases. The microstructure of the samples was investigated by using scanning electron microscopy (SEM), time-of-flight secondary ion mass spectroscopy (TOF-SIMS), transmission electron microscopy-based energy-dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS), as well as X-ray diffraction (XRD) measurements. Based on the phases observed in different temperature ranges, a sequence of the phase transitions can be established, showing that in a realistic process, when freely cooling the sample with the furnace from high to room temperature, a microstructure having spinodal-like decomposition can also be expected. The elemental mapping and magnetic behaviors of this decomposed structure are also studied.
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| 2. |
- Vida, Adam, et al.
(författare)
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Evolution of the phase structure after different heat treatments in NiCoFeCrGa high entropy alloy
- 2018
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Ingår i: Journal of Alloys and Compounds. - : Elsevier. - 0925-8388 .- 1873-4669. ; 743, s. 234-239
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Tidskriftsartikel (refereegranskat)abstract
- The non-equilibrium nature of a two-phase NiCoFeCrGa high entropy alloy (HEA) is studied by analyzing its microstructures after different heat-treatment conditions. The microstructure - containing a mixture of well-separated FCC and BCC regions - of the as-cast alloy has changed strongly by heat-treatment for 1 h at 1150 K, significantly changing the ratio of the volume fraction of the FCC and BCC phases. Needle like BCC phase particles evolved inside the original FCC regions when cooling the heat-treated samples to room temperature by rapid or medium rates. In the case of slow cooling, the original BCC regions transformed into a mixture of a matrix and cube-like BCC phase precipitates, which can be attributed to the effect of the transition between para-and ferromagnetism around the Curie-point. There is also an unambiguous correlation between the cooling rate and mechanical properties of the heat-treated alloys.
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