Core structure and strengthening mechanism of the misfit dislocation in nickel-based superalloys during high-temperature and low-stress creep

Misfit dislocation structures are investigated in a nickel-based single crystal superalloy subjected to 38.8 h creep at 1100 degrees C and 130 MPa using conventional and high resolution transmission electron microscopy (HRTEM). The misfit dislocation was identified as an uncommon one with Burgers vector b = a/2[(2) over bar 11], which can be described as inserting (or extracting) one (1 (1) over bar1) half plane and one (11 (1) over bar) half plane. This dislocation was decomposed into two partial dislocations b(1) and b(2), with b(1) = a/2[(1) over bar 01] and b(2) = a/2[(2) over bar 11]. Partial dislocations b(1) and b(2) were arranged in a "V" shape, connected by the antiphase boundary (APB), which could hinder the dislocation motion to achieve the effect of dislocation enhancement. (c) 2018 Elsevier B.V. All rights reserved.