Quantum mechanics

Shock wave

Anisotropy

Slip (aerodynamics)

Materials science

Shock (circulatory)

Thermodynamics

Physics

Alloy

Microstructure

Internal medicine

Condensed matter physics

Composite material

Crystallography

Medicine

Chemistry

Nucleation

Dislocation

Crystal twinning

Scripta Materialia

We perform molecular dynamics simulations to investigate shock-induced amorphization in CoCrNi, a medium entropy alloy (MEA) and its mean-field variant without lattice distortion. We show that a critical velocity exists above which amorphization occurs. At a low shock velocity of 800 m/s, dislocation slip and twins dominate and amorphization does not happen, but as the shock velocity increases, the deformation mechanism transitions from slip and twinning to solid-state amorphization. Under ultra-high shock velocities, extensive amorphization occurs, following the precursor of shock wave, eliminating anisotropy in spall strength. Compared to the mean-field model, lattice distortion in the MEA causes substantially more amorphization, resulting in a lower spall strength, since voids nucleate and grow preferentially in the amorphous regions.

Shock-induced amorphization in medium entropy alloy CoCrNi