The Effect of Cr on Phase Transformation Behavior of Austenite in Fe-20Mn-9Al-1.2C-xCr Low-density Steels During Isothermal Aging

Jianlei Zhang,Yueshan Jiang,Conghui Hu,Gang Ji,Changjiang Song,Qijie Zhai 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11

The influence of Cr on the microstructural evolution of austenite in Fe-20Mn-9Al-1.2C-xCr (wt%, x = 0, 3 and 6) low-densitysteels during isothermal aging at 650 °C for various durations was systematically investigated. With the isothermal agingprocessed, the 0Cr and 3Cr samples underwent the divorced eutectoid transformation followed by the eutectoid transformation,while only the eutectoid transformation was observed in the 6Cr sample. Meanwhile, increasing Cr content changedthe eutectoid transformation products from ferrite + κ-carbide in the 0Cr sample to ferrite + κ-carbide + M23C6carbide in the3Cr sample, and to ferrite + M7C3carbide in the 6Cr sample. The Cr addition significantly increased the A1 temperature (655°C) of the 0Cr sample to 712 °C of the 3Cr sample, and to 841 °C of the 6Cr sample. As a result, the temperature differencebetween the A1 temperature and experimental phase transformation temperature (650 °C) was enlarged, which provided agreater driving force for the eutectoid transformation and accelerated the transformation rate of eutectoid transformation. Inaddition, the Cr addition had a significant effect on the diffusion of constituent elements, decreased the interlayer spacingof pearlite structure from 625 ± 30 nm in the 0Cr sample to 385 ± 25 nm in the 3Cr sample, and to 150 ± 20 nm in the 6Crsample, refining the eutectoid structure. These findings revealed the mechanism regarding the effect of Cr addition on theeutectoid transformation of austenite, offering valuable insights into the microstructure design of high-performance lowdensitysteels.

Comparison of volatile components in fresh and dried Zanthoxylum bungeanum Maxim

Wenlin Zhang,Si Tan,Wanpeng Xi,Jianlei Yang,Qinhong Liao,Jianbin Lan,Yukui Lv,Jianmin Tang 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.4

Fresh and dried Zanthoxylum bungeanumMaxim volatiles of two main cultivars including Dahongpaoand Meihuajiao, were determined through GC–MS andcompared. In all the tested samples, linalool, D-limonene,eucalyptol, 3-nonanone, and b-myrcene were identified asthe five predominant components. The percentages of thesecomponents in fresh Dahongpao were 23.89%, 21.04%,7.46%, 5.63% and 5.87%, respectively. Similar percentages,27.28%, 17.62%, 6.39%, 1.66% and 7.8%, werefound in dried Dahongpao. In general, the contents oflinalool and b-myrcene in dried Dahongpao and Meihuajiaowere slightly higher than those in fresh samples,whereas the contents of D-limonene, eucalyptol, and3-nonanone were lower. Partial least squares discriminantanalysis results showed that the two cultivars could beclearly differentiated based on volatiles, whereas, the freshand dried Zanthoxylum bungeanum Maxim samples couldnot. This demonstrated that the drying process had nosignificant effect on the volatiles.

Extraordinary Bending Formability of Mg–2.5Nd–0.5Zn–0.5Zr Alloy Sheet Through Pulsed Current

Wencong Zhang,Songhui Wang,Jinqi Pan,Jianlei Yang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11

The pulsed current effect on the bending formability and microstructure evolution of the Mg–2.5Nd–0.5Zn–0.5Zr (wt%)alloy sheet was systematically studied at near room temperature (20 ~ 45 ℃). The results showed that the bending ability ofthe alloy could be significantly improved by the pulsed current. Specifically, compared with the non-electrically-assistedbending, the limiting bending depth (from 5.05 to 14.82 mm) and limiting bending angle(from 57 to 145°) of the alloy wereincreased by 193.5% and 154.3%, respectively, and the bending yield strength (from 252 to 162 MPa) decreased by 35.7%. When the peak current density was 12.1 A/mm2 (EA12), the limiting bending angle reached 145°, and there was no crackon the outer surface of the bending sample. The main reason was that the pulsed current promoted the dislocation movement,which was conducive to the activation of basal slip and non-basal slip to maintain deformation compatibility. Thedeformation mechanism of electrically-assisted bending samples showed that {10–12} twin dominated in the compressionzone, while basal slip dominated in the tension zone. In addition, the effects of peak current density on microstructure,texture evolution and fracture mechanism were analyzed in detail. It provided important theoretical guidance for masteringthe bending-forming mechanism of rare-earth magnesium alloys.

Improvement on Mechanical Properties of a bcc Matrix Al8(FeCuCrMn)92 High-Entropy Alloy by Phase Modulation of Interstitial Carbon Element

Conghui Hu,Jianlei Zhang,Yunhu Zhang,Ke Han,Changjiang Song,Qijie Zhai 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2

High-entropy alloys (HEAs) are novel multi-element alloys based on five or more constituent elements in a range of 5–35 at%. Here we present a method to improve strength of a body-centered cubic (bcc) matrix HEA without loss of ductility. Theimprovement was achieved by phase modulation combined other strengthening effect of interstitial carbon addition. Carbonaddition can enhance strength and retain good ductility in some steels because carbon increases the volume fraction offace-centered cubic (fcc) phase. We used the same principle to design and fabricate a set of Al8(FeCuCrMn)92Cx (x = 0, 1,2, 3, 4 at%) HEAs under near-rapid solidification. Our results showed that carbon addition modulated constituent phases byincreasing the volume fraction of fcc phase and carbides. As a result, addition of carbon increased yield strength of this bccmatrix HEA. But the ductility decreased, especially when carbon content was higher than 3 at%, which was ascribed to unevendistribution of Cu-rich fcc phase and carbides precipitated in bcc phase region. After annealing at 1173 K for 2 h, additionof 1 at% carbon improved yield strength without compressive fracture. It demonstrated that a proper carbon content additionwith annealing can enhance the yield strength without loss of ductility for this bcc matrix HEA. Thus, interstitial carbon additionis a meaningful method to improve the mechanical properties by phase modulation combined other strengthening effect.

Prediction of Pharmacokinetics and Penetration of Moxifloxacin in Human with Intra-Abdominal Infection Based on Extrapolated PBPK Model

Zhu, LiQin,Yang, JianWei,Zhang, Yuan,Wang, YongMing,Zhang, JianLei,Zhao, YuanYuan,Dong, WeiLin The Korean Society of Pharmacology 2015 The Korean Journal of Physiology & Pharmacology Vol.19 No.2

The aim of this study is to develop a physiologically based pharmacokinetic (PBPK) model in intra-abdominal infected rats, and extrapolate it to human to predict moxifloxacin pharmacokinetics profiles in various tissues in intra-abdominal infected human. 12 male rats with intra- abdominal infections, induced by Escherichia coli, received a single dose of 40 mg/kg body weight of moxifloxacin. Blood plasma was collected at 5, 10, 20, 30, 60, 120, 240, 480, 1440 min after drug injection. A PBPK model was developed in rats and extrapolated to human using GastroPlus software. The predictions were assessed by comparing predictions and observations. In the plasma concentration versus time profile of moxifloxcinin rats, $C_{max}$ was $11.151{\mu}g/mL$ at 5 min after the intravenous injection and $t_{1/2}$ was 2.936 h. Plasma concentration and kinetics in human were predicted and compared with observed datas. Moxifloxacin penetrated and accumulated with high concentrations in redmarrow, lung, skin, heart, liver, kidney, spleen, muscle tissues in human with intra-abdominal infection. The predicted tissue to plasma concentration ratios in abdominal viscera were between 1.1 and 2.2. When rat plasma concentrations were known, extrapolation of a PBPK model was a method to predict drug pharmacokinetics and penetration in human. Moxifloxacin has a good penetration into liver, kidney, spleen, as well as other tissues in intra-abdominal infected human. Close monitoring are necessary when using moxifloxacin due to its high concentration distribution. This pathological model extrapolation may provide reference to the PK/PD study of antibacterial agents.

Achieving Ultra-High-Strength and Good Ductility of the ZK60 Alloy Sheet by High Strain-Rate Rolling

Songhui Wang,Wencong Zhang,Jianlei Yang,Xeuyan Jiao,Jinqi Pan,Guannan Chu,Xiangyu Dai 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4

A superior combination of the ultra-high tensile strength (~ 419.9 MPa), the yield strength (~ 376.9 MPa) and the elongation(~ 14.8%) ZK60 sheet was successfully achieved by high-strain rate rolling. The ultrahigh strength was attributed to theuniform ultrafine-grained structure. The excellent ductility was ascribed to the ultrafine grains, low dislocation density andweakened basal texture in the final structure.

Prediction of Pharmacokinetics and Penetration of Moxifloxacin in Human with Intra-Abdominal Infection Based on Extrapolated PBPK Model

LiQin Zhu,JianWei Yang,Yuan Zhang,YongMing Wang,JianLei Zhang,YuanYuan Zhao,WeiLin Dong 대한약리학회 2015 The Korean Journal of Physiology & Pharmacology Vol.19 No.2

The aim of this study is to develop a physiologically based pharmacokinetic (PBPK) model in intraabdominalinfected rats, and extrapolate it to human to predict moxifloxacin pharmacokinetics profilesin various tissues in intra-abdominal infected human. 12 male rats with intra- abdominal infections,induced by Escherichia coli, received a single dose of 40 mg/kg body weight of moxifloxacin. Bloodplasma was collected at 5, 10, 20, 30, 60, 120, 240, 480, 1440 min after drug injection. A PBPK modelwas developed in rats and extrapolated to human using GastroPlus software. The predictions wereassessed by comparing predictions and observations. In the plasma concentration versus time profileof moxifloxcinin rats, Cmax was 11.151 μg/mL at 5 min after the intravenous injection and t1/2 was2.936 h. Plasma concentration and kinetics in human were predicted and compared with observed datas. Moxifloxacin penetrated and accumulated with high concentrations in redmarrow, lung, skin, heart,liver, kidney, spleen, muscle tissues in human with intra-abdominal infection. The predicted tissue toplasma concentration ratios in abdominal viscera were between 1.1 and 2.2. When rat plasma concentrationswere known, extrapolation of a PBPK model was a method to predict drug pharmacokineticsand penetration in human. Moxifloxacin has a good penetration into liver, kidney, spleen, as well asother tissues in intra-abdominal infected human. Close monitoring are necessary when using moxifloxacindue to its high concentration distribution. This pathological model extrapolation may provide referenceto the PK/PD study of antibacterial agents.