Interface structure of (130) twin in the U-14.0 at.% Nb alloy: an experimental and theoretical study

In this work, we report an experimental and theoretical study of the (130) twin system in the U-14.0 at.% Nb alloy using aberration-corrected TEM in combination with first-principles calculations. We clearly give the atomic structure of (130) twin and its twin boundary energy for the first time. We evidence that the widely used (130) twin system in pseudo-orthorhombic system is in fact the (101) twin system in the monoclinic crystal system. Through first-principles calculations, we also find that the local atomic structure of Nb significantly affects the twin boundary energy due to the depleted charge zone at Nb atom and charge-rich zone around Nb atom. These results may help us better understand the deformation mechanism in low-symmetry U metal and U-Nb alloys.