Figure 2. Interfacial structures for two orientation relationships.

All projections are along . The dislocations are indexed by the “⊥” symbol and its Burgers vector is depicted using Burgers circuit (dash line circuits). (a–d), HRTEM images and MD simulations of the γ/α′ interface with Pitsch OR (a,c) and K-S2 OR (b,d), respectively. (a,c), The Pitsch OR interface with (220)γ//(121)α′. Two sets of dislocations on (111)γ planes and on planes, distribute with an average distance of and 9 (002)γ planes to release the lattice misfit strain between them. (b,d), The K-S2 OR interface with , requiring the rotated to rotate back from the Pitsch OR. To achieve this, another two sets of dislocations, with Burgers vectors of -b⁽¹⁾ and -b⁽²⁾, respectively, are generated to form b⁽¹⁾ and -b⁽¹⁾ and b⁽²⁾ and -b⁽²⁾ dislocation dipoles (dash-lined “⊥” symbol dipoles with opposite sign). The number of -b⁽¹⁾ dislocations is almost the same as the number of b⁽¹⁾ dislocations, with only one un-coupled b⁽¹⁾ dislocation, thereby making the unrotated to evolve to the (110)α′. The single b⁽²⁾ on every 19^th plane releases the lattice misfit strain of 5% between (111)γ and (110)α′. (e–g), HRTEM image taken at an α′/α′ interface, showing a 5.26° rotation inside one α′ inclusion, from the Pitsch OR to K-S OR along the interface plane. (e), Two sets of dislocations walls on (110)α′ planes and on planes, form the diffuse small-angle tilt grain boundary. More dislocations are located in the left region of zone I, where the average dislocation spacing D of 12.5 Å meets the requirement in the OR change. (f, g), The enlarged image in two pink-color framed rectangular zones I and II in (e), respectively. No dislocations are found in these regions and the lattice is continuously bending-mode deformed, leading to the diffuse interface region bent obviously and the plane rotated 5.26°. All scale bars, 2 nm.