Influence of severe plastic deformation on the microstructure and hardness of a CoCrFeNi high-entropy alloy: A comparison with CoCrFeNiMn

Microstructural Investigation of Nanocrystalline Hydrogen-Storing Mg-Titanate Nanotube Composites Processed by High-Pressure Torsion

“…It is also noted that a slight increase can be observed of the MgTN_3h_N3 disk. As the HPT procedure imposes inhomogeneous strain along the radius of the disk, smaller revolution numbers can result in a deformation-dependent structure [52] and mechanical properties [53], however, larger rotations can homogenize the material [54,55]. Therefore, we chose the disks that performed for N = 3 rotations for subsequent investigations.…”

High-Pressure Torsion for Synthesis of High-Entropy Alloys

“…This first study on the synthesis of high-entropy hydrogen storage materials by the HPT method confirmed the potential of the method, although the reported hydrogen storage capacity was not high, as shown in Figure 4. Since recent studies suggested the potential of high-entropy hydrogen storage materials (HfNbTiVZr [86], TiZrNbHfTa [87], MgZr-TiFe0.5Co0.5Ni0.5 [88], TiZrNbMoV [89], TiZrHfScMo [90], CoFeMnTiVZr [91], ZrTiVCrFeNi [92], (VFe)60(TiCrCo)40−xZrx [93], TiVZrNbTa [94], AlCrFeMnNiW [95]) and particularly those materials designated by inputs from the theoretical calculations (TiZrCrMnFeNi [59], TiZrNbFeNi [96], and TiZrNbCrFe [97]), a combination of theoretical design and mechanical synthesis by HPT processing should be an effective strategy to explore new hydrogen storage materials. Edalati et al [59] and Floriano et al [96] suggested three criteria to explore high-entropy materials for room-temperature hydrogen storage: (i) selection of an AB2 or AB system, where A represents the hydride-forming elements such as Mg, Ti, Zr, V, Nb, etc., and B represents elements with low chemical [78], with permission from ELSEVIER, 2021.…”

“…Since recent studies suggested the potential of high-entropy hydrogen storage materials (HfNbTiVZr [86], TiZrNbHfTa [87], MgZrTiFe 0.5 Co 0.5 Ni 0.5 [88], TiZrNbMoV [89], TiZrHfScMo [90], CoFeMnTiVZr [91], ZrTiVCrFeNi [92], (VFe) 60 (TiCrCo) 40−x Zr x [93], TiVZrNbTa [94], AlCrFeMnNiW [95]) and particularly those materials designated by inputs from the theoretical calculations (TiZrCrMnFeNi [59], TiZrNbFeNi [96], and TiZrN-bCrFe [97]), a combination of theoretical design and mechanical synthesis by HPT processing should be an effective strategy to explore new hydrogen storage materials. Edalati et al [59] and Floriano et al [96] suggested three criteria to explore high-entropy materials for roomtemperature hydrogen storage: (i) selection of an AB 2 or AB system, where A represents the hydride-forming elements such as Mg, Ti, Zr, V, Nb, etc., and B represents elements with low chemical affinity with hydrogen, such as Cr, Mn, Fe, Co, Ni, etc. ; (ii) valence electron concentration of 6.4-6.5; (iii) Laves phase stability, which should be examined by thermodynamic calculations using the CALPHAD (calculation of phase diagram) method.…”

“…; (ii) valence electron concentration of 6.4-6.5; (iii) Laves phase stability, which should be examined by thermodynamic calculations using the CALPHAD (calculation of phase diagram) method. Although these suggested criteria were used successfully to design room-temperature hydrogen storage materials [59,96], there are some less successful attempts to design HEAs with higher A/B ratio with the Laves or BCC structures [75,97].…”

“…Although HEAs have generally high strength [47][48][49][50], it was shown that their strength can be further enhanced by SPD processing. For example, the HPT method was successfully used for the hardening of several HEAs, such as CoCrFeMnNi [51,52], Al 0.3 CoCrFeNi [53,54], Al 0.5 CoCrFeMnNi [55], AlCrFeCoNiNb [56], TiZrNbHfTa [57], CrFe 2 NiMnV0.25 [58], CoCrFeNi [59], TiZrCrMn-FeNi [60], TiAlFeCoNi [61], TiAlFeCoNi-C [62] and CoCrFeMnNi-C [63]. More recently, the HPT method was used to impart ultra-SPD and synthesize CoCrFeMnNi with high hardness [64].…”