Correlation of particle impact conditions with bonding, nanocrystal formation and mechanical properties in kinetic sprayed nickel

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

“…The impact velocities of the particles were estimated empirically as $ 560 m s À 1 [6]. The purity of the powder was 499.5 wt% as reported by the product datasheet, and the chemical composition of the powder is shown in Table 1.…”

“…Samples with a thickness of $1.4 mm were prepared by depositing a commercially pure Ni powder (with a mean particle size of $35 mm) using a kinetic spraying system with powder preheating at a temperature of $ 873 K (for details, see [6]). The impact velocities of the particles were estimated empirically as $ 560 m s À 1 [6].…”

“…This finding is surprising, as the deposit was formed at a high particle impact temperature ( $ 873 K) [6]. An understanding of the causes behind this abnormal phenomenon will allow us to expand our understanding of the mechanisms of the ultrahigh-strain-rate deformation of metals with medium to high SFEs (e.g., Ni).…”

“…Kinetic spray (or cold spray) is a relatively low temperature and high deposition rate process, in which micron-sized metallic powder particles impact the substrate or previously deposited layer at high velocities and subsequently bond together metallurgically and/or mechanically within several tens of nanoseconds by strain-induced adiabatic heating and shear instabilities at the localized interface [1][2][3][4][5][6][7][8][9]. During this process, the particles are subjected to severe plastic deformation (SPD) at ultrahigh strain rates ( $10 6 -10 9 s À 1 ) upon impact, giving rise to strain localization at the interface [2][3][4][5][6][7][8][9][10].…”

“…During this process, the particles are subjected to severe plastic deformation (SPD) at ultrahigh strain rates ( $10 6 -10 9 s À 1 ) upon impact, giving rise to strain localization at the interface [2][3][4][5][6][7][8][9][10]. Due to the specific characteristics of the deformation process, various interfacial phenomena such as localized melting [3,4], dynamic recovery (DRV) and dynamic recrystallization (DRX) [5][6][7][8][9], amorphization [7,10], and deformation twinning [5] have been reported.…”