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Alam K, Jang W, Jeong G, Ser J, Kang D, Kim TH, Cho H. Synthesis of High-Entropy Alloys with a Tailored Composition and Phase Structure Using a Single Configurable Target. ACS OMEGA 2024; 9:1362-1374. [PMID: 38222601 PMCID: PMC10785334 DOI: 10.1021/acsomega.3c07721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/11/2023] [Accepted: 12/13/2023] [Indexed: 01/16/2024]
Abstract
Previously, refractory high-entropy alloys (HEAs) with high crystallinity were synthesized using a configurable target without heat treatment. This study builds upon prior investigations to develop nonrefractory elemental HEAs with low crystallinity using a novel target system. Different targets with various elemental compositions, i.e., Co20Cr20Ni20Mn20Mo20 (target 1), Co30Cr15Ni25Mn15Mo15 (target 2), and Co15Cr25Cu20Mn20Ni20 (target 3), are designed to modify the phase structure. The elemental composition is varied to ensure face-centered cubic (FCC) or body-centered cubic (BCC) phase stabilization. In target 1, the FCC and BCC phases coexist, whereas targets 2 and 3 are characterized by a single FCC phase. Thin films based on targets 1 and 2 exhibit crystalline phases followed by annealing, as indicated by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. In contrast, target 3 yields crystalline thin films without any heat treatment. The thin-film coatings are classified based on the atomic size difference (δ). The δ value for the target with the elemental composition CoCrMoMnNi is 9.7, i.e., ≥6.6, corresponding to an HEA with an amorphous phase. However, the annealed thin film is considered a multiprincipal elemental alloy. In contrast, δ for the CoCrCuMnNi HEA is 5, i.e., ≤6.6, upon the substitution of Mo with Cu, and a solid solution phase is formed without any heat treatment. Thus, the degree of crystallinity can be controlled through heat treatment and the manipulation of δ in the absence of heat treatment. The XRD results clarify the crystallinity and phase structure, indicating the presence of FCC or a combination of FCC and BCC phases. The outcomes are consistent with those obtained through the analysis of the valence electron concentration based on X-ray photoelectron spectroscopy. Furthermore, a selected area electron diffraction analysis confirms the presence of both amorphous and crystalline structures in the HEA thin films. Additionally, phase evolution and segregation are observed at 500 °C.
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Affiliation(s)
- Khurshed Alam
- School
of Materials Science & Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
- Department
of Metal Powder, Korea Institute of Materials
Science, 51508 Changwon, South Korea
| | - Woohyung Jang
- Department
of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju 61186, Korea
| | - Geonwoo Jeong
- School
of Materials Science & Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Jinhui Ser
- School
of Materials Science & Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
- Gordon
Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Doori Kang
- School
of Materials Science & Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Tae-Hoon Kim
- School
of Materials Science & Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Hoonsung Cho
- School
of Materials Science & Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
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Das G, Chaturvedi S, Naqash TA, Hussain MW, Saquib S, Suleman G, Sindi AS, Shafi S, Sharif RA. Comparative in-vitro microscopic evaluation of vertical marginal discrepancy, microhardness, and surface roughness of nickel-chromium in new and recast alloy. Sci Rep 2023; 13:16673. [PMID: 37794022 PMCID: PMC10551011 DOI: 10.1038/s41598-023-40377-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/09/2023] [Indexed: 10/06/2023] Open
Abstract
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.
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Affiliation(s)
- Gotam Das
- Department of Prosthodontics, College of Dentistry, King Khalid University, 61421, Abha, Saudi Arabia.
| | - Saurabh Chaturvedi
- Department of Prosthodontics, College of Dentistry, King Khalid University, 61421, Abha, Saudi Arabia
| | - Talib Amin Naqash
- Department of Prosthodontics, College of Dentistry, King Khalid University, 61421, Abha, Saudi Arabia
| | - Muhammad Waqar Hussain
- Department of Prosthodontics, Bakhtawar Amin Medical and Dental College, Multan, Pakistan
| | - Shahabe Saquib
- Department of periodontics, Datta Maghe Institute of Higher Education & Research, Deemed to be University, Warda, 442001, India
| | - Ghazala Suleman
- Department of Prosthodontics, College of Dentistry, King Khalid University, 61421, Abha, Saudi Arabia
| | - Abdulelah Sameer Sindi
- Department of Restorative Dental Sciences, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Shabina Shafi
- Specialist Pediatric Dentist, Saudi Dent Group Khamis Mushayt, Mushait, Saudi Arabia
| | - Rania A Sharif
- Department of Prosthodontics, College of Dentistry, King Khalid University, 61421, Abha, Saudi Arabia
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