The effect of interstitial carbon on the mechanical properties and dislocation substructure evolution in Fe40.4Ni11.3Mn34.8Al7.5Cr6 high entropy alloys

Abstract

A systematic study of the effects of up to 1.1 at. % carbon on the mechanical properties and evolution of the dislocation substructure in a series of a high entropy alloys (HEA) based on Fe 40.4 Ni 11.3 Mn 34.8 Al 7.5 Cr 6 is presented. Transmission electron microscopy (TEM), synchrotron X-ray diffraction (XRD) and atom probe tomography (APT) were used to show that all the alloys are single-phase f.c.c. random solid solutions. The lattice constant, determined from synchrotron XRD measurements, increases linearly with increasing carbon concentration, which leads to a linear relationship between the yield strength and the carbon concentration. The dislocation substructures, as determined by a TEM, show a transition from wavy slip to planar slip and, at higher strains, and from cellforming structure (dislocations cells, cell blocks and dense dislocation walls) to non-cell forming structure (Taylor lattice, microbands and domain boundaries) with the addition of carbon, features related to the increase in lattice friction stress. The stacking fault energy (measured via weak-beam imaging of the separation of dislocation partials) decreases with increasing carbon content, which also contributes to the transition from wavy slip to planar slip. The formation of non-cell forming structure induced by carbon 3 leads to a high degree of strain hardening and a substantial increase in the ultimate tensile strength. The consequent postponement of necking due to the high strain hardening, along with the plasticity accommodation arising from the formation of microbands and domain boundaries, result in an increase of ductility due to the carbon addition.

Cryogenic strength improvement by utilizing room-temperature deformation twinning in a partially recrystallized VCrMnFeCoNi high-entropy alloy

“…However, such twinning is difficult to achieve at room temperature because the resolved shear stress is insufficient to reach the critical stress for twinning2021. Another issue is the relatively low yield strength (0.2–0.6 GPa) caused by the fcc structural characteristics of the alloy1420222324. Here, we effectively induce twinning in an HEA at room temperature and exploit the induced twinning to improve the cryogenic tensile properties, particularly the yield strength, of the material.…”

Effects of Different Levels of Boron on Microstructure and Hardness of CoCrFeNiAlxCu0.7Si0.1By High-Entropy Alloy Coatings by Laser Cladding

“…This is because the interstitial atom can produce a lattice asymmetric distortion, and the substitutional solute is spherically symmetric in crystal lattice distortions. However, most studies have found that brittle boride precipitation is unavoidable by arc melting preparation, and it is difficult to obtain high boron solubility in the boron-containing HEAs [1][2][3]. The results of this paper prove that laser rapid solidification can play an effective role in preventing the precipitation of the boride phase in HEA coatings.…”

“…Nevertheless, previous studies utilized an arc melting technique to prepare bulk alloy, and reported that the complex brittle boride precipitation is inevitable after solidification in the HEAs, due to high thermodynamic enthalpy of the boride compound [1,6,7]. In comparison to the dominant arc melting synthesis technique, the laser cladding technique-which has a rapid solidification rate of 10 3 -10 6 • C/s-has a greater ability to prepare high performance HEA coatings in engineering applications [8,9].…”

“…However, boride precipitation seems unavoidable in traditional alloys, owing to the strong binding energy between small atomic boron and metallic elements [1]. Recently, newly designed high entropy alloys (HEAs) with multi-principal elements are a breakthrough to the conventional alloying concept [2,3].…”

Plastic dynamics of the Al0.5CoCrCuFeNi high entropy alloy at cryogenic temperatures: Jerky flow, stair-like fluctuation, scaling behavior, and non-chaotic state

“…[1][2][3][4] It has been reported that HEAs exhibit many attractive properties, such as good ductility, high hardness, strong oxidation resistance, wonderful corrosion resistance, superior resistance to temper softening, super wear resistance, strong fatigue, and fracture resistance. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] These remarkable properties make HEAs suitable advanced structural materials for many industries, including aerospace and ocean engineering.…”