Achieving high ductility in the 1.7 GPa grade CoCrFeMnNi high-entropy alloy at 77 K

Compositional Design of Soft Magnetic High Entropy Alloys by Minimizing Magnetostriction Coefficient in (Fe0.3Co0.5Ni0.2)100−x(Al1/3Si2/3)x System

“…Consequently, HEAs show promising potentials for wide ranges of industrial applications and the HEA concept is considered to be one of the three major breakthroughs in alloying theory [3]. To date considerable research efforts on HEAs focus on their microstructures and mechanical properties [26][27][28][29][30][31] while there is rising interest in developing high-entropy soft magnetic materials [32][33][34][35][36][37][38][39][40]. Magnetic materials play a fundamental role in transformers, motors, electromagnets, and other power industries [41].…”

Temperature and load-ratio dependent fatigue-crack growth in the CrMnFeCoNi high-entropy alloy

“…However, this effect, we believe, derives from a completely different mechanism, that of the enhancement of (roughness-induced) crack closure at lower temperatures due to the onset of a rougher, more facetted, intergranular fatigue fracture mode. Irrespective of the prevailing mechanisms though, the damage-tolerant properties of the CrMnFeCoNi high-entropy alloy, with respect to both subcritical cracking (fatigue) resistance and the crack-initiation and growth fracture toughnesses at tensile strengths exceeding 1 GPa [14][15][16][17][18][19], are exceptional and comparable, or even exceed, the best metallic structural materials reported to date. Indeed, the Cantor alloy shows outstanding promise for numerous structural applications, particularly under cryogenic conditions.…”

“…The CrMnFeCoNi alloy, developed by Cantor and coworkers [2], is almost certainly the most studied high-entropy alloy to date, principally because it has been shown to display exceptional mechanical properties of high strength, ductility and fracture toughness, which are all increased at cryogenic temperatures [3,[14][15][16][17]. Although the mechanisms underlying such behavior are complex involving a synergy of differing deformation processes [16,33], a prime mechanism appears to involve the onset of deformation nano-twinning at lower temperatures which serves to enhance strain hardening to promote strength and ductility, the latter by delaying the onset of plastic instability or necking [14][15][16][17]. In light of this, it is of interest that we show here that similarly the fatigue-crack propagation resistance, specifically the value of the ∆Kth fatigue threshold, is also increased at cryogenic temperatures in this alloy.…”

“…A particularly notable HEA is the transition metal-based 'Cantor alloy' CrMnFeCoNi, a single-phase, face-centered cubic (fcc) solid-solution alloy which displays exceptional mechanical properties [2,11,14]. This alloy shows tensile strengths upwards of ~ 1 GPa, tensile ductilities of ~60 to 70%, and high fracture toughness values exceeding 200 MPa√m, which are further enhanced at cryogenic temperatures [14][15][16][17], properties that are comparable to, or exceed, those of cryogenic steels [15][16][17][18].…”

“…While the uniaxial tensile and toughness properties of CrMnFeCoNi and other highentropy alloys are now well characterized [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], corresponding studies on the fatigue properties are sparse, despite the fact that potential applications of these alloys as future structural materials will invariably depend upon their fatigue resistance, which dictates component lifetimes. Prior work on the Cantor alloy has provided measurements of the highcycle fatigue behavior of recrystallized CrMnFeCoNi at a single load ratio at 293 and 198 K [19] whereas other studies on cast Al-containing CrCoNi-based variants have focused on stress-life and crack propagation behavior [20,21].…”