Deformation twinning and twinning related fracture in coarse-grained α-uranium

An investigation of deformation twinning in coarse-grained α-uranium was conducted within the heat-affected zone of weld specimens tested in tension. Twins and twin interactions were studied both at fracture surfaces and sub-surface, using transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The fracture surface plane was identified using TEM of foils cut from the fracture surface using a focused ion beam. Intersecting twins found in these foils were also analyzed. EBSD was also used to analyze twins and twin interactions at and below the fracture surface. Fracture parallel to {1 7 2} twin planes and {1 7 2} twin crossings were observed, in agreement with previous optical/Laue diffraction studies. Previously unobserved crossings of {1 7 2} twins by {1 1 2} twins were also frequently observed. These twin interactions are interpreted in terms of previously established crystallographic criteria for twin crossings.