Dynamic Impact Behaviour of High Entropy Alloys Used in the Military Domain

Dynamic response of high-entropy alloys to ballistic impact

“…However, in situ observations of dynamic response of the HEAs to ballistic impact are in lack or very limited for further fundamental understanding, and the influence of chemical composition to the alloys’ ballistic performance is not included in the experimental studies. Combining with finite element simulations to investigate the dynamic response of a HEA, Al x CrFeCoNi y , to bullet impact, Geantă et al ( 31 ) performed bullet impact tests and showed that the ballistic resistance of the HEA was largely influenced by its chemical composition. However, this simulation method is ineffective to well reveal the dynamic behavior of HEA, since the numerical method is based on given mechanical properties.…”

Characterization and Testing of High-Entropy Alloys from AlCrFeCoNi System for Military Applications

“…The hardness of the experimental materials was determined using the Shimadzu HMV2T microhardness apparatus in Lamet Laboratories from Politehnica University of Bucharest. The measurements were made in line, with mark distances of about 500 μm, using the fingerprint force of 0.1 N and pressing time of 10 seconds [9][10][11][12]. For the Al x Cr y Fe z Co v Ni w system, the entire spectrum of microhardness values in the x = y = z = v = w = 0.2 … 2 at% range was analyzed, as shown in Figure 4.…”

“…High-entropy alloys from the AlCrFeCoNi system feature very good mechanical properties for military applications, as shown in Table 1. Thus, the yield stress, the compressive strength, and the plastic deformation of these alloys reach unexpected values [8][9][10][11][12][13][14][15][16][17][18][19][20], making them usable as composite structures, resistant to dynamic stresses with high deformation velocity, applicable in the field of collective protection [9][10][11][12][13][14][15][16][17][18][19][20].…”

High Entropy Alloys for Medical Applications

“…HEAs are defined as alloys comprising more than five main elements mixed in an equiatomic or near-equiatomic fraction [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Many HEAs have been reported to have: superior mechanical properties, such as ultrahigh fracture even at high temperatures, high hardness, toughness exceeding that of most pure metals and alloys, excellent comparable strength to that of structural ceramics and some metallic glasses, exceptional ductility, and fracture toughness at cryogenic temperatures [1,3], and good physical properties, such as superconductivity, supermagnetism, and significant resistance to corrosion [5].…”

“…Furthermore, the decrease or increase in the ratio of additional elements can generate different metallographic structures with significant influences on the properties of alloys [6][7][8][9][10]. While high-strength conventional alloys are based mainly on the controlled distribution of one or two high-hardness phases at most, in high entropy alloys, the exceptional properties are based on the quenching effect of the supersaturated solid solution and on the suppression of the intermetallic phases [1,[4][5][6][7][8][9][10][11][12]. The complex distribution of the various chemical elements within the crystalline network of high entropy alloys appears to be the main cause of their special characteristics when compared to the classical or bi-component alloys.…”