Dynamic mechanical behaviors of metallic glass-shape memory alloy bilayered nanocomposite under shock wave compression

It has been extensively reported that metallic glass-shape memory alloy (MG-SMA) composites possess superior ductility and strength. Here, shock responses of bilayered MG-SMA (Cu50Zr50-B2 CuZr) nanocomposites are investigated by atomistic simulations. The results show that the MG/SMA interface can reflect compression/rarefaction waves, depending on the shock direction. Higher shear stress of the SMA means it has stronger shear resistance than the MG. At the velocity of 0.8 km/s, a B2 to BCT phase transformation is shown in the SMA regions, which is more obvious in the monocrystalline than that in the nanocrystalline regions because the grain boundary compression and grain rotation assimilate substantial plastic strain. At the velocity of 1.6 km/s, a two-stage phase transformation of B2 to BCT to amorphous structure is captured in the monocrystalline SMA. But for the nanocrystalline SMAs, the B2 phase is rapidly amorphized due to the promoting effects of the grain boundary.