Effects of Cr/Ni ratio on physical properties of Cr-Mn-Fe-Co-Ni high-entropy alloys

Luo

et al. 2023

Mater. Res. Express

The physical nature of the scratch behavior of CoCrFeMnNi HEA and its deformation mechanism at different morphology densities are investigated by molecular dynamics (MD) simulations. The results show that the groove morphology contributes to the reduction of surface plastic deformation and exhibits a friction-reducing effect. As the morphology density decreases, the surface deformation and atom pile-up decrease, and the plastic deformation in the scratch region decreases, resulting in a further enhancement of the friction reduction effect. The increase of scratch depth intensifies the plastic deformation of the specimens, and the average scratch coefficient of friction increases with the increase in scratch depth. The dominant plastic deformation mechanism in the scratch deformation of CoCrFeMnNi HEA with different morphology densities is the slip deformation of Shockley partial dislocations. The MD simulations are verified further by qualitatively comparing them with corresponding experimental observations of CoCrFeMnNi HEA.

Section: Validation Of Simulation Resultsmentioning

confidence: 99%

Atomistic study on the nano-scratch mechanism of CoCrFeMnNi high-entropy alloy at different morphology densities

Luo

et al. 2023

Mater. Res. Express

“…The In the current study, the changes in marginal discrepancy were as small as 48.12 ± 0.474µm for the new mixture compared to the recast mixture with different percentages: 25% old (67.9822 ± 0.965µm), 50% old (226.12 ± 2.213µm), and 94.60%±7µm old (140.72 ± 1.605µm). (Wagner C et al 2022) calculated the physical characteristics of base metal alloys and suggested that they can be used for four generations without signi cant variation. (Nandish et al 2020) con rmed that there was no signi cant deterioration in Ni-Cr alloy recasting for up to 10 generations, and that mixing used metal with new metal and recasting 100 times did not create signi cant deteriorating changes in the base materials, microstructure, or clinical quality.…”

Section: Resultsmentioning

confidence: 99%

“…The authors stressed the importance of adhering to uncontaminated materials to reduce pollution and negative impacts on the material. (Wagner C et al 2022) con rmed that easily oxidized compounds are dispersed without throwing and mixing with oxygen because the metal near the surface changes in alloy formation. The changes described in the statement may occur concurrently during the second stage and may affect the disintegration of the mixture.…”

Section: Resultsmentioning

confidence: 99%

Comparative in-vitro Microscopic Evaluation of Vertical Marginal Discrepancy, Microhardness, and Surface Roughness of Nickel-chromium in New and Recast Alloy

Das

2023

Preprint

In the restoration of the partial dentition the casting alloy plays a major role. The alloys used require the long term stay in oral cavity exposed to a wet environment, so they must have good wear resistance, biocompatibility, and mechanically good strength. The objective of the study is to evaluate the vertical marginal discrepancy, surface roughness and microhardness of the new and recast nickel-chromium (base metal) alloys. 125 wax patterns were fabricated from a customized stainless steel master die with a heavy chamfer cervical margin divided into 5 groups. Each group had 25 samples. Group A: twenty five wax patterns were cast using 100% by weight of new alloy, Group B: casting was done by using 75% new alloy and 25% alloy by weight, Group C: wax patterns were cast using 50% new alloy and 50% alloy, Group D: 25% new alloy and 75% alloy and Group E: 100% recast alloy. Induction castings were finished and seated on the die. The vertical marginal discrepancy was measured by analytical scanning microscope, microhardness were tested on universal testing machine and surface roughness on tester of surface roughness. The maximum vertical marginal discrepancy and surface roughness was found in group E while minimum was in group A. The mean maximum microhardness was found in group C while minimum was in group B (p < 0.001). Castings produced using new alloy were better than those obtained with recast alloy. This indicated that recasting of (Ni–Cr) can be used as a good alternative for the new alloy from an economical point of view.

“…In the current study, the changes in marginal discrepancy were as small as 48.12 ± 0.474 μm for the new mixture compared to the recast mixture with different percentages: 25% old (67.9822 ± 0.965 μm), 50% old (226.12 ± 2.213 μm), and 94.60% ± 7 μm old (140.72 ± 1.605 μm). Wagner et al 21 calculated the physical characteristics of base metal alloys and suggested that they can be used for four generations without significant variation. Nandishet al 22 confirmed that there was no significant deterioration in Ni–Cr alloy recasting for up to 10 generations, and that mixing used metal with new metal and recasting 100 times did not create significant deteriorating changes in the base materials, microstructure, or clinical quality.…”

Section: Discussionmentioning

confidence: 99%

Comparative in-vitro microscopic evaluation of vertical marginal discrepancy, microhardness, and surface roughness of nickel–chromium in new and recast alloy

Das,

chaturvedi,

Naqash

et al. 2023

Sci Rep

Reusing of alloy has become a need of time due to the increasing demand, depletion of resources, and substantial increase in their price. The alloys used require a long-term stay in the oral cavity exposed to a wet environment, so they must have good wear resistance, biocompatibility, and mechanically good strength. In this study, the vertical marginal discrepancy, surface roughness, and microhardness of the new and recast nickel–chromium (base metal) alloys were evaluated. 125 wax patterns were fabricated from a customized stainless steel master die with a heavy chamfer cervical margin divided into 5 groups. Each group had 25 samples. Group A: 25 wax patterns were cast using 100% by weight of new alloy, Group B: the casting was done by using 75% new alloy and 25% alloy by weight, Group C: wax patterns were cast using 50% new alloy and 50% alloy, Group D: 25% new alloy and 75% alloy and Group E: 100% recast alloy. The vertical marginal discrepancy was measured by an analytical scanning microscope, microhardness was tested on a universal testing machine, and surface roughness was on a tester of surface roughness. Castings produced using new alloys were better than those obtained with reused alloys. Alloys can be reused till 50% by weight along with the new alloy and accelerated casting technique can be used to save the lab time to fabricate castings with acceptable vertical marginal discrepancy, microhardness, and surface roughness. This indicated that 50% recasting of (Ni–Cr) can be used as a good alternative for the new alloy from an economical point of view.