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Ashutosh Sharma,Hansung Lee,Byungmin Ahn 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9
In this study, equimolar AlCuSiFe-x (x = Cr, Mn, Zn, Sn) HEAs were fabricated by mechanical alloying (MA) and sparkplasma sintering methods (SPS). The MA was performed for 45 h followed by densification of powder compacts at 650 °C. The results revealed the formation of dual face-centered cubic (FCC) and body-centered cubic (BCC) structures in AlCuSiFex(x = Zn, Sn) while a single BCC solid solution was noticed in AlCuSiFe-x (x = Cr, Mn). After SPS treatment, AlCuSiFeSnalloy contained FCC with CuxSnywhile AlCuSiFe–Zn changed to FCC + BCC structure. Similarly, AlCuSiFeCr andAlCuSiFeMn showed the formation of BCC + FCC with additional σ- and μ-phases in the HEA matrix. The calculated thermodynamicparameters of HEAs also supported the formation of different solid-solution phases in each of the above HEAs. It was found that HEAs with the additive elements Sn and Zn tend to have major FCC phases, while those with Cr and Mngive rise to major BCC with brittle σ- and μ-phase, which further improves their mechanical strength.
SiC based Technology for High Power Electronics and Packaging Applications
Ashutosh Sharma,이순재,장영주,정재필 한국마이크로전자및패키징학회 2014 마이크로전자 및 패키징학회지 Vol.20 No.2
Silicon has been most widely used semiconductor material for power electronic systems. However, Si-basedpower devices have attained their working limits and there are a lot of efforts for alternative Si-based power devices forbetter performance. Advances in power electronics have improved the efficiency, size, weight and materials cost. Newwide band gap materials such as SiC have now been introduced for high power applications. SiC power devices havebeen evolved from lab scale to a viable alternative to Si electronics in high-efficiency and high-power density applications. In this article, the potential impact of SiC devices for power applications will be discussed along with their Si counterpartin terms of higher switching performance, higher voltages and higher power density. The recent progress in thedevelopment of high voltage power semiconductor devices is reviewed. Future trends in device development andindustrialization are also addressed.
Ashutosh Sharma,Ashok K. Srivastava,Kwan Lee,Byungmin Ahn 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4
Lead-free Sn–58Bi– x CeO 2 ( x in wt% = 0, 0.3, 0.6 and 0.9) composite solder was prepared via mechanical blending andmelting route. The ceria nanoparticles (CeO 2 ) were prepared from chemical precipitation method. Further, the variationin microstructure and phase composition, melting point, wetting and mechanical properties were studied through scanningelectron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diff erential scanning calorimetry,spreading ratio, contact angle and tensile testing, respectively. It was shown that Sn–58Bi– x CeO 2 composite solders show16.66 and 32.05% increase in spread ratio and wetting angle, respectively, due to the enhanced melt fl uidity up to x = 0.6. The fraction of hard Bi-phase was also refi ned simultaneously. The tensile results showed a slight decrease in ultimatetensile strength and enhancement in ductility up to x = 0.3 and 0.6 except at x = 0.9. High temperature aging also demonstrateda reduced intermetallic compounds thickness when fraction of ceria nanoparticles in the matrix was up to x = 0.6. Itis suggested that for optimum set of soldering properties, the concentration of the nanoparticles should be at 0.6 wt% in themonolithic Sn–58Bi alloy.