Atomic-scale understanding of the unilateral thickening of γ lamellae during α to γ phase transformation in Ti48Al2Cr2Nb alloy

摘要

The unilateral thickening of gamma lamellae during alpha to gamma transformation was investigated by examinations of surface reliefs and atomic steps of gamma lamellae. The results show that the rounded corners of terraces and the steps prefer to form mainly on one side of the gamma lamella, and Shockley partial dislocations with same and with very random Burgers vectors construct the steps. It indicates gamma lamellae grow in a mixture of two scenarios of Shockley partial dislocations. The differences of gamma/alpha interface stability and element concentration on the two sides of gamma lamella contribute to the unilateral thickening. (C) 2018 Elsevier B.V. All rights reserved.