Ballistic Impact Response of Al_0.1CoCrFeNi High‐Entropy Alloy

Abstract

Figure 4. a) Low-magnification SEM image of full penetration condition; b) SEM image of region 1 showing cracks parallel to the crater edge; c) IPF map of region 2 showing highly deformed grains; d) Zoomed-in region 2 IPF map showing the formation of recrystallized grains; e) SEM image of region 3 showing deformation bands near the exit region, the features indicated with yellow arrows show microtwins; f) nano-indentation hardness map for full penetration condition.

Excellent ballistic impact resistance of Al0.3CoCrFeNi multi-principal element alloy with unique bimodal microstructure

“…High velocity impact showed a smooth exit hole with large petal formation. This indicates ductile hole growth type of failure mode, which is typically seen in target materials with good ductility 11 , 37 . During ductile hole growth, the target material absorbs the kinetic energy from the projectile through plastic deformation and maximizes the resistance to projectile penetration for a given strength level 11 , 37 .…”

“…A diamond Berkovich indenter at a peak load of 10 mN with loading and unloading rates of 2 mN/s and a hold time of 2 s was used for indentation mapping. The neighboring indents were separated by ~ 200 μm to avoid overlap of their plastic zones and to capture the hardness maps with high resolution over a large area 11 , 25 .…”

“…Low strain rate (in the range of 10 −4 s −1 –10 −2 s −1 ) and dynamic strain rate (in the range of 10 1 s −1 –10 3 s −1 ) response of HEAs has been extensively studied for the fundamental understanding of their plastic deformation mechanisms 7 – 10 . Previous studies focused on single phase HEAs have demonstrated that the deformation mechanisms, strain hardening, flow stress, and strain rate sensitivity are strongly influenced by the strain rate 11 – 13 , owing to the unique combination of solid solution strengthening, twinning, dislocation mediated plasticity, and stress-induced phase transitions 14 . Al x CoCrFeNi alloys have been widely studied as a model system due to their desirable microstructure, ranging from single-phase to multi-phase solid solutions, obtained with a slight change in aluminum content 5 , 15 – 18 .…”

“…The deformation mechanism in several HEAs has been reported to transition from dislocation-mediated to twinning-induced plasticity with increase in strain rate. Twin boundaries act as barriers for dislocation movement and increase the strain hardenability 11 . The ability for twinning depends on the stacking fault energy (SFE), which for several FCC-based HEAs has been reported to be in the range of 20 to 30 mJ/m 2 20 .…”

Al0.5CoCrFeNi2 High Entropy Alloy Particle Reinforced AZ91 Magnesium Alloy-Based Composite Processed by Spark Plasma Sintering

“…HEAs can be classified into 3D transition metal HEAs, 4f transition metal HEAs, refractory metal HEAs and light metal HEAs [ 10 ]. Among different series of HEAs, the one based on principle elements of Al, Co, Cr, Fe and Ni has been extensively studied for its microstructure, phase stability and mechanical properties [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Equiatomic AlCoCrFeNi HEA is a dual-phase (FCC and BCC) material, and it undergoes a phase transformation at high temperature [ 17 ].…”