Nanoscale deformation twinning at ultrahigh strain rates during kinetic spraying of nickel

Nanoscale twins parallel to the {111} planes were observed to be formed by deformation twinning in a nano-sized grain during kinetic spraying of nickel (>99.5% purity) at ultrahigh strain rates (>107 s−1), high strain levels (>100%) and high temperatures (>873 K). An interfacial region dominated by strain hardening over thermal softening upon impact, as shown by finite element simulations, is considered to facilitate twinning with the aid of the effects of small amounts of solute atoms and nanocrystalline/amorphous nickel oxides trapped at local interfaces.

► Nickel was deposited via kinetic spraying at a particle impact temperature of ∼873 K.
► Nanoscale deformation twins were generated at ultrahigh strain rates (>107 s−1).
► Local interfacial region subjected to dominant strain hardening favors twinning.