Grain boundary migration during abnormal grain growth in nanocrystalline Ni

Study of rapid grain boundary migration in a nanocrystalline Ni thin film

“…Similar studies on abnormal grain growth in Ni using in situ TEM have been carried out, notably by Hibbard et al [9,40]. The results from that study were similar in that the sporadic and unpredictable behavior of grain growth was observed.…”

Microstructure stability and evolution in CVD carbonyl Ni materials upon annealing – Grain growth and detwinning process

“…The free surfaces of TEM thin foil near the jet-polished hole, where the microstructure is observed, are considered to provide a strong dragging force for twin and grain boundaries to migrate. Similar observation was reported where the TEM foil surface actually inhibited the grain boundary migration in nanocrystalline nickel during the in situ TEM annealing experiment [37]. Novikov simulated the grain growth in films on the substrate where all the grains were in columnar shape with only the diameters different [38].…”

“…In the present as-deposited CVD nickel, the microstructure observation indicates those high density twin containing columnar grains near the jet-polished hole of the TEM sample must run through the thickness. The diameter of these columnar grains is estimated to be 2-12 mm as reported above, whereas the thinned region near the hole is only about one to two nano-grain thick [37]. Hence, the ratio of grain diameter to the film thickness in the present case is much higher than 3, above which complete stagnation of grain boundaries would occur as modeled by Novikov [38].…”

Local Crystallographic Orientation Correlation Measurements Connecting the Processing and Properties of Face-Centered Cubic Metals

“…form. This abnormal grain growth is expected for pure nanocrystalline metals and is a mechanism for reducing excess boundary energy [275,276]. To preserve this study's focus on nanocrystalline phenomena, the abnormally grown grains were excluded from the TKD analysis.…”