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 °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 ¯ 11 ] , which can be described as inserting (or extracting) one ( 1 1 ¯ 1 ) half plane and one ( 11 1 ¯ ) half plane. This dislocation was decomposed into two partial dislocations b 1 and b 2 , with b 1  = a/2 [ 1 ¯ 01 ] and b 2  = a/2 [ 1 ¯ 10 ] . 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. [ABSTRACT FROM AUTHOR]