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Quantitative Analysis of Cryomilled Nanocrystalline Ti-6Al-4V Alloy Powder by X-Ray Diffraction

Oh M., Yu H. K., Lee J.-H., Oh M. C., Jung S.-H., Ahn B.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1439--1442

EN

A nanocrystalline Ti alloy powder was fabricated using cryomilling. The grain size and lattice strain evolution during cryomilling were quantitatively analyzed using X-ray diffraction (XRD) based on the Scherrer equation, Williamson-Hall (W-H) plotting method, and size-strain (S-S) method assuming uniform deformation. Other physical parameters including stress and strain have been calculated. The average crystallite size and the lattice strain evaluated from XRD analysis are in good agreement with the result of transmission electron microscopy (TEM).

2

Transient Liquid Phase Behavior of Sn-Coated Cu Particles and Chip Bonding using Paste Containing the Particles

Hwang J. H., Lee J.-H.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1143--1148

EN

Sn-coated Cu particles were prepared as a filler material for transient liquid phase (TLP) bonding. The thickness of Sn coating was controlled by controlling the number of plating cycles. The Sn-coated Cu particles best suited for TLP bonding were fabricated by Sn plating thrice, and the particles showed a pronounced endothermic peak at 232°C. The heating of the particles for just 10 s at 250°C destroyed the initial core-shell structure and encouraged the formation of Cu-Sn intermetallic compounds. Further, die bonding was also successfully performed at 250°C under a slight bonding pressure of around 0.1 MPa using a paste containing the particles. The bonding time of 30 s facilitated the bonding of Sn-coated Cu particles to the Au surface and also increased the probability of network formation between particles.

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Preparation of Submicroscale Ag-Coated Cu Particles by Multi-Step Addition of Ag Plating Solution and Antioxidation Properties for Different Ag Shell Thicknesses

Choi E. B., Lee J.-H.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1137--1142

EN

For application as a low-cost conductive filler material, submicroscale Cu@Ag particles were fabricated at room temperature without any reductants by a multi-step addition method using an ethylene glycol-based Ag plating solution. Scanning electron microscopy images of the Ag-coated Cu particles demonstrated the formation of discrete Ag particles less than 100 nm in size as well as a thin Ag coating on Cu particles, during the early addition steps. However, as the thickness of the Ag coating increased, the small Ag particles agglomerated into Ag coatings with an increase in the number of Ag plating steps. Owing to the absence of additives such as surfactants, a comparison between the microstructural images and calculations indicated increased agglomeration between fabricated Ag-coated Cu particles with an increase in the number of Ag plating steps. However, thermogravimetric-differential scanning calorimetry of the agglomerated Ag-coated Cu particles after the fifth addition of the Ag plating solution demonstrated their antioxidation behavior even after 70 min in air at 150°C.

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Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures

Lee J.-H., Kim D.-O., Lee K.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1191--1196

EN

The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA) steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s-1 and 1.0 s-1. A long plateau region appeared for the 0.002 s-1 strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s-1 strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient (n), strength constant (K), and activation energy (Q), obtained from the flow stress curves were applied to the power law of plastic deformation. The constitutive model for flow stress can be expressed as σ = (39.8 ln (Z) – 716.6) · ε(−0.00955ln(Z) + 0.4930) for the 1.0 s-1 strain rate and σ = (19.9ln (Z) – 592.3) · ε(−0.00212ln(Z) + 0.1540) for the 0.002 s-1 strain rate.

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A validated HPLC–MS/MS method for the quantification of supinoxin in rat plasma and its application to pharmacokinetic study

Jeong J.-W., Seol Y.-H., Hyun H.-Ch., Kim H.-R., Lee J.-H., Gong Y.-D., Kang N.-S., Koo T.-S.

Acta Chromatographica

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2017

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Vol. 29, no. 4

463--468

EN

A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the quantification of an anticancer drug, supinoxin (RX-5902), in rat plasma. Following precipitation pretreatment using 0.1% formic acid in acetonitrile, separation was performed using a reverse phase liquid chromatography column packed with C18 (3.5 μm, 2.1 × 50 mm) along with a mobile phase of 0.1% formic acid in distilled water and 0.1% formic acid in acetonitrile at a flow rate of 0.3 mL min-1. Detection was achieved using MS/MS by multiple reaction monitoring via an electrospray ionization source at mass/charge transitions of m/z 442.30 → 223.30 for supinoxin and m/z 430.08 → 223.20 for the internal standard DGG-200064. This method demonstrated a linear standard curve (r = 0.9980) over a supinoxin concentration range of 0.0005–1 μg Ml-1, as well as intra- and inter-assay precisions below 7.08% and 13.74%, respectively, and an accuracy of 1.15–4.50%. The matrix effect, recovery, and process efficiency were 93.63%, 99.70%, and 93.33%, respectively. Thus, a sensitive and reliable LC–MS/MS method was developed and validated for the quantification of supinoxin in rat plasma. This method was successfully applied to the evaluation of pharmacokinetic studies after single intravenous and oral administration of 1 mg kg-1 supinoxin in rats.