Direct atomic-scale visualization of growth and dissolution of γNb5Si3 in an Nb-Ti-Si based alloy via in-situ transmission electron microscopy.

Abstract Precipitation and dissolution of γNb 5 Si 3 precipitates in an Nb-Ti-Si based alloy has been visualized by atomic-scale in-situ heating transmission electron microscopy. Nanoscale γNb 5 Si 3 precipitates nucleate inside Nbss around 850 °C with two orientation relationships (ORs): (200) Nb // 1 1 ¯ 00 γ (OR-I) and 10 1 ¯ Nb // 1 1 ¯ 00 γ (OR-II). Growth and dissolution of the two orientational γNb 5 Si 3 precipitates are promoted by motion of atomic steps and facets at interfaces. Precipitates along OR-I is less stable than that of OR-II, adopting dissolution temperature of 1125 °C and 1250 °C respectively. The orientational stability of γNb 5 Si 3 precipitates, which is correlated with planar disregistry, affects their evolution behavior directly upon heating. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]