The Cr-Doped Ni-YSZ(111) interface: Segregation, oxidation and the Ni equilibrium crystal shape

Nahor, Hadar; Kauffmann, Yaron; Kaplan, Wayne D.

doi:10.1016/j.actamat.2018.12.023

Cited by 8 publications

(3 citation statements)

References 25 publications

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“…It is worth mentioning two recent papers in the literature that attempt to explore the impact of an alloying element on the microstructure of a metallic thin film in contact with an oxide plane. They investigated films of fcc binary alloys which were prepared by stacking of pure layers on single-crystal oxide planes (Ni-Cr on YSZ [83] and Ni-Fe on c-sapphire [84]). Although interfacial segregation of Cr [83] has been observed, there was no change of the preferred OR of Ni on YSZ since it was already dictated by the Ni layer that had been deposited in contact with the oxide crystal before Cr segregation occurred.…”

Section: Preferred Orientation Relationship Of the Cocrfeni Grains Onmentioning

confidence: 99%

“…They investigated films of fcc binary alloys which were prepared by stacking of pure layers on single-crystal oxide planes (Ni-Cr on YSZ [83] and Ni-Fe on c-sapphire [84]). Although interfacial segregation of Cr [83] has been observed, there was no change of the preferred OR of Ni on YSZ since it was already dictated by the Ni layer that had been deposited in contact with the oxide crystal before Cr segregation occurred. The same situation stands for Ni-Fe alloy where Ni was also the as-deposited layer in contact with csapphire.…”

Section: Preferred Orientation Relationship Of the Cocrfeni Grains Onmentioning

confidence: 99%

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Microstructure evolution and thermal stability of equiatomic CoCrFeNi films on (0001) α-Al2O3

et al. 2020

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Homogeneous face-centered cubic (fcc) polycrystalline CoCrFeNi films were deposited at room temperature on (0001) a-Al 2 O 3 (c-sapphire). Phase and morphological stability of 200 to 670 nm thick films were investigated between 973 K and 1423 K. The fcc-phase persists while the original <111> texture of 30-100 nm wide columnar grains evolves into ~10 or ~1000 µm wide grains upon annealing. Only the metallic M grains having two specific orientation relationships (ORs) to the c-sapphire grow. These ORs are OR1 (M(111)[110]//a-Al 2 O 3 (0001)[1100]) and OR2 (M(111)[110]//a-Al 2 O 3 (0001)[1120]) and their twin-related variants (OR1t and OR2t). They are identical to those reported for several pure fcc metal (M) films. Thus, the ORs in these fcc/c-sapphire systems appear not to be controlled by the fcc phase chemistry or its lattice parameter as usually assumed in literature. Upon annealing, the films either retain their integrity or break-up depending on the competing kinetics of grain growth and grain boundary grooving. Triple junctions of the grain boundaries, the major actors in film stability, were tracked. Thinner films and higher temperatures favor film break-up by dewetting from the holes grooved at the triple junctions down to the substrate. Below 1000 K, the film microstructure stabilizes into 10 µm wide OR1 and OR1t twin grains independent of film thickness. Above 1000 K, the OR2 and OR2t grains expand to sizes exceeding more than a 1000 times the film thickness. The grain boundaries of the OR2 and OR2t grains migrate fast enough to overcome the nucleation of holes from which break-up could initiate. The growth of the OR2 and OR2t grains in this complex alloy is faster than in pure fcc metals at equivalent homologous annealing temperatures.

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Section: Preferred Orientation Relationship Of the Cocrfeni Grains Onmentioning

confidence: 99%

Section: Preferred Orientation Relationship Of the Cocrfeni Grains Onmentioning

confidence: 99%

Microstructure evolution and thermal stability of equiatomic CoCrFeNi films on (0001) α-Al2O3

et al. 2020

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“…On the other hand, YSZ-spinel and YSZ-alumina heterointerfaces do not show any segregation. This is an interesting observation because segregation is known to occur at other heterointerfaces, such as metal-ceramic systems like Cr-doped Ni/YSZ [46] , MgO/Cu(Ag) [47] , Al alloy-B 4 C [48] . In most of such interfacial segregation stud- ies based on dissimilar phases, a dopant/alloying element added to the metal segregates to lower the total grain boundary energy.…”

Section: Scanning Transmission Electron Microscopy (Stem) -Energy Dispersive X-ray Spectroscopy (Eds) Characterizationmentioning

confidence: 99%

Correlations of grain boundary segregation to sintering techniques in a three-phase ceramic

Syed

Ohtaki

et al. 2020

Materialia

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The effects of using different sintering techniques (conventional, flash and spark plasma sintering) on grain boundary segregation were investigated in a 3-phase polycrystalline ceramic containing cubic 8 mol% Y 2 O 3 stabilized ZrO 2 (YSZ), -Al 2 O 3 and MgAl 2 O 4 . Six types of interfaces for each sintered sample were analyzed for grain boundary chemistry. Using aberration-corrected STEM and EDS, we show Al segregation at YSZ-YSZ boundaries, and Y/Zr segregation at Al 2 O 3 -Al 2 O 3 , MgAl 2 O 4 -MgAl 2 O 4 and MgAl 2 O 4 -Al 2 O 3 boundaries. YSZ-MgAl 2 O 4 and YSZ-Al 2 O 3 heterointerfaces, in contrast, do not show elemental segregation. Our results show that the type of segregation at different boundaries does not change with different sintering processes, indicating that elemental segregation mainly depends on initial sample composition, although the amount of segregation can vary. Quantitative analyses reveal that spark plasma sintering (950°C for 5 min, 100 MPa) results in relatively higher average segregation at grain boundaries and heterointerfaces compared to conventional sintering (1550°C for 10 h), suggesting that low temperatures result in higher grain boundary segregation. The average segregation concentrations at the grain boundaries of our flash sintered sample (estimated to reach 1700°C for 6 s) were found to be consistently similar to long-annealed spark-plasma sintered sample (1350°C for 20 h), suggesting that very high temperatures reached during flash process can achieve similar segregation concentrations compared to a SPS sample annealed for several hours at lower temperature. The presence of other phases in multi-phase systems can modify the grain boundary chemistry and segregation compared to segregation in single-phase ceramics.

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Ca segregation at Au–YSZ interfaces

2019

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The Cr-Doped Ni-YSZ(111) interface: Segregation, oxidation and the Ni equilibrium crystal shape

Cited by 8 publications

References 25 publications

Microstructure evolution and thermal stability of equiatomic CoCrFeNi films on (0001) α-Al2O3

Microstructure evolution and thermal stability of equiatomic CoCrFeNi films on (0001) α-Al2O3

Correlations of grain boundary segregation to sintering techniques in a three-phase ceramic

Ca segregation at Au–YSZ interfaces

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