Shock Loading of Granular Ni/Al Composites. Part 2: Shock-Induced Chemistry

Abstract

We use molecular dynamics simulations to characterize the chemical processes resulting from the shock compaction of a loosely packed granular reactive composite of Ni and Al. For all of the impact strengths studied (with piston velocities u p in the range 0.5–2.5 km/s), we find that reactions initiate in the vicinity of the collapsed pores. For the lowest impact velocities (u p ≤ 0.75 km/s), the reactions that initiate at the collapsed pores subsequently slow down as thermal transport dissipates the initial temperature excursion and outpaces the exothermic energy release rate. At intermediate impact velocities (u p ≈ 1.0 km/s), the localization of thermal kinetic energy is sufficient to establish a reaction rate that is self-sustaining in exothermic energy release, and the sample reacts within a few nanoseconds. At the highest impact velocities (u p ≥ 1.5 km/s), the localization of translational kinetic energy as well as thermal energy following pore collapse drives the rapid propagation of the reaction from the collapsed pores.

Three-Dimensional Integrated X-ray Diffraction Imaging of a Native Strain in Multi-Layered WSe2

“…As bulk structures approach the few-layer or monolayer limit, it is well-known that the mechanical properties, degree of orbital interactions and electronic band dispersion of the crystal structure become highly sensitive to the applied strain and their distribution. − There are several different ways in which such native strain can develop in 2-D TMDC materials. TMDC layers experience varying degree of strain during their preparation (exfoliation or growth via CVD), the transfer process and due to strong interfacial interactions in the postdeposition or post-transfer stage.…”

Mechanical behaviour and microstructural evolution of Ni-based single crystal alloys under shock loading

“…The embedded atom method (EAM) is used to simulate the microstructure evolution of Nibased single-crystal alloys. [19][20][21] Ni-based single-crystal alloys have face-centred cubic (fcc) structures that are well suited for studying using EAM methods. In this study, the potential function of a Ni-Al system was used to simulate the evolution of the microstructure under shock loading.…”

“…In this study, the potential function of a Ni-Al system was used to simulate the evolution of the microstructure under shock loading. The shock behaviour of Ni-Al alloys has been studied in literature 20,21 using the potential function of Ni-Al. Accordingly, we studied the mechanical behaviour and microstructure evolution of Nibased single crystal alloys under shock loading.…”

Reactivity of Ni–Al nanocomposites prepared by mechanical activation: A molecular dynamics study

“…Preliminary attempts to examine the reactivity of activated systems have been carried out in specific cases. der particles and the subsequent reactivity [15][16][17][18] . Here, the rise in temperature is a consequence of the impact, contrary to the case of a classic SHS process.…”