Spallation damage of 90W–Ni–Fe alloy under laser-induced plasma shock wave

Abstract

Laser shock loading is a more promising technology for investigating spallation damage in materials under shock-wave loading. In this paper, shock-induced spallation in a 90W–Ni–Fe alloy at an ultrahigh tensile strain rate of 106 s−1 is investigated using a superintense ultrafast laser facility. The spallation of the 90W–Ni–Fe alloy was dominated by a transgranular fracture of tungsten(W) particles with a high spall strength of 6.46 GPa. Here, we found an interesting phenomenon that the formation of nanograins inside W particles leads to a new mode of transcrystalline fracture of W particles during the laser shock loading. Futhermore, most voids were nucleated inside the W particles rather than at the W/γ-(Ni, Fe) matrix-phase interface. This result contradicts the fracture theory under quasi-static loading, which posits that the W/γ-(Ni, Fe) matrix-phase interface is not the preferred site for the initial failure under shock loading.

Keywords

• Laser shock
• Tungsten alloy
• Spallation
• Shock impedance