Twin interface structures and formation mechanisms of the topologically close-packed phase within refractory Nb-Ni binary alloy

The peritectic μ -Nb 7 Ni 6 phase was prepared directly from liquid Nb 54 Ni 46 alloy by melting spinning technique. The atomic resolution image reveals the presence of complex atomic arrangements, including both {0001} stacking faults and twins. Notably, the crystallographic slipping plane does not coincide with the crystallographic twinning plane of the {0001} twin. Furthermore, the density functional theory calculation indicates that the formation of the {0001} twin arises from the synergistic effect of slipping on (0006) crystallographic slipping plane with the Burgers vector b ​= ​1/3< 1 ¯ 100>, combined with local atomic rearrangements at the 3 a and 6 c 2 sites along the [0001] direction during slipping. Finally, the twinning mechanism of the {0001} twin was elucidated by integrating the atomic model of the μ -Nb 7 Ni 6 phase, the atomic resolution images and density functional theory calculation results, the slipping of three consecutive neighboring (0006) planes along [ 1 ¯ 100] direction will form two adjacent {0001} twin interfaces separated by a distance of c.