Homogenization of Al CoCrFeNi high-entropy alloys with improved corrosion resistance

Microstructure and properties of CoCrNi medium-entropy alloy produced by gas atomization and spark plasma sintering

“…High entropy alloys (HEAs), consisting of at least five equiatomic or near-equiatomic elements crystalized as simple solid solution structures, have attracted significant interest owing to their unique phase structures and superior properties. [1][2][3][4][5][6] For example, the typical simple FCC CoCrFeNiMn HEA generally exhibited excellent tensile strength (above 1 GPa) and fracture toughness (exceeding 200 MPa•m 1/2 ). 7 The AlxCoCrFeNi HEAs exhibit superior corrosion resistance, compared to those of conventional corrosion-resistant alloys, such as stainless steels and Al, Ni, Ti, and Cu alloys.…”

“…7 The AlxCoCrFeNi HEAs exhibit superior corrosion resistance, compared to those of conventional corrosion-resistant alloys, such as stainless steels and Al, Ni, Ti, and Cu alloys. 6 Nevertheless, the origin of the formation of simple solid solution structures and answer on whether more elements improve the mechanical properties of HEAs are still controversial. The explanation of development of simple solid solution structures rather than intermetallic phases by increasing the number of elements to obtain a higher entropy might be wrong, as demonstrated by related experimental and CALPHAD simulation results.…”

Nanostructured high-entropy materials

“…It has been demonstrated that CoCrFeNiCu with a grain size of 29 nm exhibits poorer corrosion resistance than CoCrFeNi with similar grain size, suggesting Cu is not an ideal candidate elemental addition in HEA systems for corrosion resistance [80,95,96]. Such an effect is also prevalent in Al-containing alloys, where significant segregation in Al x CoCrFeNi promotes the formation of BCC precipitates 50-100 nm in size within a uniform FCC matrix with increasing Al content, which in turn act as localized galvanic cells [90]. Compounding the effects of Al and Cu segregation, an increase in Al content in the Al x CoCrCuFeNi system has expectedly been shown to decrease its corrosion resistance [95].…”

The AC Soft Magnetic Properties of FeCoNixCuAl (1.0 ≤ x ≤ 1.75) High-Entropy Alloys

“…The HEAs are conducive to the formation of a solid solution phase, typically with a structure of a body-centred cubic (BCC) [5,6], a face-centred cubic (FCC) [7][8][9], a hexagonal stacked (HCP) [10,11], or a mixture of the above mentioned structures [12][13][14]. In the past decade, HEAs have drawn extensive attention because of their excellent mechanical and chemical properties, such as great thermal stability [15], good corrosion resistance [16,17], good wear resistance [18], excellent strength [19] and high hardness [20]. Some HEAs show soft magnetic properties due to their ferromagnetic elements such as Fe, Co and Ni [21][22][23][24][25].…”