Spallation damage of tungsten heavy alloy under shock loading.

• The spall strength of tungsten alloy is weakly dependent on the peak stress. • With the increase of impact stress, cleavage fracture replaces intergranular fracture as the main fracture mode. • Twins appear near the crack of tungsten particles, which hinders the further propagation of cracks. • The {100}, {110} and {111} planes are the most potent macroscopic cleavage planes for the tungsten alloy. In this study, plate-impact experiments are conducted using tungsten heavy alloy (WHA) to obtain the free-surface velocity profiles under shock stress of 6–23 GPa. By analyzing the velocity wave profile, it is demonstrated that the spall strength is weakly dependent on the peak stress. The microstructure of the recovered WHA is well characterized and it's observed that intergranular fracture and cleavage are the primary fracture mechanisms. Deformation twins are sparsely distributed near the cleavage crack. The existence of twin boundary not only affects crack propagation but also regulates the crack path and reinitiates the cleavage propagation direction on the twin boundary. The macroscopic cleavage facet planes are detected to be {100}, {110} and {111} at all shock stress. [ABSTRACT FROM AUTHOR]