Effect of Addition of Rare Earth Elements on the Microstructure, Texture, and Mechanical Properties of Extruded ZK60 Alloy

S. Najafi,M. Sabbaghian,A. Sheikhani,P. Nagy,K. Fekete,J. Gubicza 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.6

Microstructure, texture and mechanical properties of extruded ZK60 alloys containing different rare earth (RE) elementswere studied. Two alloys containing 1 and 2 wt% Ce-rich lanthanides as well as two other alloys with 1 and 2 wt% Y wereprepared and denoted as ZK60–1RE, ZK60–2RE, ZK60–1Y and ZK60–2Y, respectively. The results showed that the additionof RE elements refined the grain size of the ZK60 alloy, and Y had a more significant effect on the grain size reduction. The finer grain size in the ZK60–1Y and ZK60–2Y alloys (2.3 and 2.1 μm, respectively) compared to ZK60–1RE andZK60–2RE alloys (6.2 and 3.7 μm, respectively) was attributed to the pinning effect of very fine secondary phases on grainboundaries. While the ZK60–1Y alloy exhibited a fiber texture with a slight rotation of < 1010 > poles around the extrusiondirection, the ZK60–1RE alloy showed a new texture component known as RE texture. Moreover, there were no changes inthe fiber-like texture component of ZK60–2RE and ZK60–2Y alloys. The mechanical properties of the alloys were assessedby shear punch test. Accordingly, the addition of RE and Y elements enhanced the shear strength, and the maximum ultimateshear strength of 176 MPa was obtained for the ZK60–2RE alloy. The higher dislocation density, the lower volume fractionof dynamically recrystallized regions compared to other alloys, and the large fraction of secondary phase particles wereresponsible for this high strength value.

분말피복압연법에 의해 제조된 Al/Al₂O₃ 복합재료의 가공열처리후의 기계적 성질 및 집합조직

이성희,이충효 한국분말야금학회 2003 한국분말재료학회지 (KPMI) Vol.10 No.4

The $Al/Al_2O_3$ composites fabricated by powder in sheath rolling method were cold-rolled by 50% reduction and annealed for 1.8 ks at various temperatures ranging from 200 to 50$0^{\circ}C$, for improvement of the mechanical properties. The mechanical properties and texture of the composites after rolling and annealing were investigated. The tensile strength of the composites increased significantly due to work hardening after cold rolling, however it decreased due to restoration after annealing. The strength of the composites was improved by thermo mechanical treatment. On the other hand, the texture evolution with annealing temperatures wa,i different between the unreinforced material and the composites. The unreinforced material showed a deformation (rolling) texture of which main component is {112}<111> at annealing temperatures up to 30$0^{\circ}C$. However, the composites have already exhibited a recrystallization texture of which main component is {001}<100> after annealing at 20$0^{\circ}C$. This proves that the critical temperature for recrystailization is lower in the composites than in the unreinforced ones.

직물 색채와 역학적 성질이 시질감에 미치는 영향 - 디지털 프린팅을 중심으로 -

이안례,이은주,Lee, An Rye,Yi, Eunjou The Korean Fiber Society 2015 한국섬유공학회지 Vol.52 No.1

The objective of this study was to investigate whether color variables, such as CIE values and hue/tone categories, and mechanical properties influence the visual texture of fabric, and to establish prediction models for the visual texture based on both mechanical properties and color variables. A digital textile printing system was used to color six different silk and cotton fabrics. The chromatic shade value for each color was identified using a $3{\times}3$ matrix of hue (red, yellow, and green) or tone (pale, vivid, and grayish), with gray as the neutral value. Mechanical properties of the fabric samples were measured using a Kawabata Evaluation System. Subjective perception of visual texture by human evaluators was obtained using modified magnitude estimation. The mechanical properties of the fabric samples were found to be the primary influence on variations in sensory descriptors of the visual texture. Furthermore, results showed that, while the visual texture was strongly dependent on the tones, chromatic shade, and gray, it was hardly affected by hue. Finally, these results were used to develop prediction models for visual texture based on both mechanical properties and color variables.

Processing Properties of Korean Rice Varieties in Relation to Rice Noodle Quality

한혜민,조준현,고봉경 한국식품과학회 2011 Food Science and Biotechnology Vol.20 No.5

The purpose of this study was to investigate the physicochemical and pasting properties of rice developed in Korea in relation to noodle quality. Two indica lines (Hanareumbyeo and Chenmaai) and 7 japonica lines (Jinsumi, Goamibyeo, Manmibyeo, Milyang261, Seolgaeng,Suweon517, and YR24088 Acp9) were wet milled followed by lyophilized and passed through a 115 mesh sieve. The amylose contents were varied from 10.1 to 32.1%. Among them, Milyang261 showed unique paste viscosity although its amylose content was very high as 32.1% with poor cooking properties. Except Milyang261 and Suweon517,the high amylose content lines of Chenmaai, Goamibyeo,and YR24088 Acp9 showed desirable cooking properties in cooking loss, tensile strength, and texture profile. No item was selected as a key factor for rice noodles. However,amylose content, paste viscosity, and damaged starch could be positive components for improvement of rice noodle quality. The high amylose line of Chenmaai, YR24088Acp9, and Goamibyeo showed the most appropriate properties for making extruded rice noodles with good cooking and textural properties. The paste properties,damaged starch, and high amylose content of the flour can be used as indicators of the rice noodle quality.

Microstructure, Mechanical Properties and Strain Hardening Behavior of Alternative α/β Mg-Li Composite Sheets Prepared by Accumulative Roll Bonding

Huajie Wu,Yang Wang,Ruizhi Wu,Feng Zhong,Dan Wang,Legan Hou,Jinghuai Zhang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5

To improve comprehensive mechanical properties of Mg-Li alloy, alternative α/β Mg-Li composite sheets with a bimodalgrainedstructure were prepared by accumulative roll bonding (ARB). The microstructure, texture, mechanical propertiesand strain hardening behavior of the alternative α/β Mg-Li composite sheets were studied. The bimodal grain structure,with ultrafine grains (about 0.79 μm) in the α alloy and coarse grains (about 53.28 μm) in the β alloy, can be observed in thecomposite sheet. The dominant texture of α-Mg and β-Li alloys is {0002} basal texture and {110} texture, respectively. Inthe α alloy, the basal texture decreases gradually with the increase of ARB pass, and the non-basal texture is formed in thesheet processed by 5-pass ARB. The dislocation density of the composite sheet gradually increases and approaches saturationafter 3-pass ARB process due to the balance between dislocation accumulation in the ARB process and dislocationannihilation in dynamic recovery. The sheet processed by 3-pass ARB has the preferable strength and plasticity, with yieldstrength, ultimate tensile strength, elongation of 204 MPa, 216 MPa, 22.73%, respectively. Compared with the as-annealedalloys before ARB, the strain hardening rate of the ARB composite sheets increases gradually at low stress (stage II). Mg-Lisheets produced by ARB process remain a high plasticity because of the longer softening stage (stage III), which is mainlycontributed to the synergistic effect of the bimodal grain structure and the activation of non-basal texture.

Effect of Strain Rate on the Microstructure and Texture Evolution of the ZK60 Alloy Sheets

Hongge Yan,Qin Wu,Jihua Chen,Weijun Xia,Min Song,Bin Su,Biao Huang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.3

The dynamic recrystallization (DRX), precipitation and texture evolution of the ZK60 alloy sheets rolled at 300 °C withdifferent strain rates were studied, and the effects of texture on the plasticity were also clarified. The DRX grain sizes at fivestrain rates (5–25 s−1) are 1.4 μm, 1.2 μm, 1.8 μm, 2.4 μm and 2.8 μm, respectively, while the DRX volume fractions are35.8%, 75.0%, 82.0%, 88.0% and 93.0%, respectively. The maximum intensity values of the (0002) texture are 7.91, 8.22,7.64, 5.76 and 5.34 at five strain rates, respectively. The strongest (0002) texture is observed at the strain rate of 10 s−1,which is related to the relatively low DRX volume fraction and the precipitation density. The tensile strength (UTS) and yieldstrength (YS) increases firstly and then decreases, while the elongation (EL) gradually increases with increasing the strainrate, suggesting that the plasticity of the alloy sheet can be improved by decreasing the basal texture intensity and increasingthe dispersion degree of the basal texture. The optimal comprehensive mechanical properties are obtained at the strain rateof 10 s−1, with UTS of 358 MPa, YS of 291 MPa and EL of 21.5%.

Asymmetric and symmetric rolling of magnesium: Evolution of microstructure, texture and mechanical properties

Biswas, S.,Kim, D.I.,Suwas, S. Elsevier Sequoia 2012 Materials science & engineering. properties, micro Vol.550 No.-

In the present study, asymmetric rolling was carried out for incorporating a shear component during the rolling at different temperatures, and was compared with conventional (symmetric) rolling. The microstructures were investigated using electron back-scatter diffraction (EBSD). The strain incorporated was compared with the help of grain orientation spread (GOS). GOS was eventually used as a criterion to partition the microstructure for separating the deformed and the dynamically recrystallized (DRX) grains. The texture of the partitioned DRX grains was shifted by ~30<SUP>o</SUP> along the c-axis from the deformed grains. The mechanism of dynamic recrystallization (DRX) has been identified as continuous dynamic recovery and recrystallization (CDRR). The partitioned deformed grains for the higher temperature rolled specimens exhibited a texture similar to the room temperature rolled specimen. The asymmetric rolling introduces a shear component which shifts the texture fibre by ~5-10<SUP>o</SUP> from the conventional rolling texture. This led to an increase in ductility with little compromise on strength.

Effect of Pre-straining and Subsequent Annealing on Microstructure and Mechanical Property of Zr–Sn–Nb–Fe Zirconium Alloy

Hao Wang,Dianwu Zhou,Youruiling Yan,Jinshui Liu,Bo Gao 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.3

Zirconium alloy is extensively used in nuclear industries as cladding and core structural material. However, the formabilityand service behavior are affected due to the anisotropy of mechanical property, which is detrimental to the specific application. In this work, effect of pre-straining and subsequent annealing (PA) on microstructure and mechanical property ofZr–Sn–Nb–Fe zirconium alloy is determined by means of scanning electron microscope equipped with electron backscattersdiffraction and digital image correlation technique. It is found that the basal texture intensity and grain size of as-receivedsample decreases after pre-straining, the work-hardening value (n) increases from 0.126 of as-received sample to 0.152 ofPA samples, while the anisotropy of mechanical property decreases gradually with the increase of pre-straining level. Inaddition, the strength, ductility and work-hardening value (n) of the PA samples tend to be accordant in the transverse direction,rolling direction (RD) and the 45° direction when the pre-straining level reaches 8%. The basal texture is graduallyweakened and dispersed along the RD after annealing, whose orientation is favorable for the activation of pyramidal ⟨c + a⟩slip to accommodate to the strain in thickness direction, which leads to the lower anisotropy (featured by the r-value). Thelow r-value and high work-hardening value (n) are favorable for improving formability. Hence, microstructure and textureof zirconium alloy can be modified though appropriate PA process to improve the comprehensive properties.

호남평야지 재배시기별 찰벼 품종의 수량과 호화점도 및 식감 관련 특성 분석

박재령,서정환,이창민,박송희,진민아,정오영,백만기,박현수 한국육종학회 2023 한국육종학회지 Vol.55 No.1

The cultivated area of glutinous rice in the Homan Plain of Korea is increasing to diversify the cropping system. Depending onthe time of transplanting, glutinous rice can be divided into early, ordinary, and late cultivation. Eight glutinous rice cultivars (Baegseolchal,Baekogchal, Boramchal, Boseogchal, Dongjinchal, JJ644wx, Nunbora, and Sinseonchal) were used to evaluate yield, pasting properties, andtexture according to cultivation time and to analyze the genotype-environment relationship. There were nine yield-related, six pasting-related,and four texture-related traits studied. Heading date and culm length were shortened as cultivation time increased, while panicle length, numberof spikelets, and 1,000-grain weight increased. Furthermore, late cultivation time also reduced pasting properties, peak viscosity, trough viscosity,and final viscosity. Hardness and adhesiveness among the texture properties increased with cultivation time, but stickiness decreased. Thevariation in 1,000-grain weight is mostly dominated by genotype, whereas heading date and yield are heavily influenced by environmentalfactors. All pasting property characteristics varied with environment changes, and genotype variation was dominant for all texture properties. Boramchal yielded the most in early and ordinary cultivation and Sinseonchal, together with Boramchal, yielded the most in late cultivation. Cultivars with excellent grain quality were Sinseonchal in early cultivation and Baegseolchal and Baekogchal in ordinary and late cultivation. A comparative analysis of characteristics based on cultivation time can assist in the selection of glutinous rice suitable for the Honam Plainand in the breeding of cultivars with improved yield and excellent grain quality.

벤젠 유기물 도입에 따른 실리카 기반 에어로겔의 소수성 및 기계적 특성 연구

WANG QI,이지훈,Rushikesh P. Dhavale,최하령,김태희,박형호 한국마이크로전자및패키징학회 2020 마이크로전자 및 패키징학회지 Vol.27 No.4

The silica aerogels with benzene-bridged were designed to have uniform network structure, ordered pore structure, improved mechanical properties and excellent textural properties. Adding organic to enhance the mechanical properties of silica aerogels is a common method, but textural properties of aerogels with organic are reduced due to the organic-inorganic phase separation. In this paper, we use a simple and low-cost method to increase mechanical properties while maintaining textural properties of SiO2 aerogels. Two types of benzene-bridged precursors were prepared to study the effect of the number of hydroxyl band on the textural and mechanical properties. The porous silica aerogel was prepared by a simple, cost effective and pollution-free sol-gel method. This method does not require additional silylating reagents. The benzene-bridged silica aerogel samples prepared had excellent textural properties, high specific surface area (1,326 m2/g), porous structure and hydrophobicity (>140°). The mechanical strength of 2T4 is more than 5 times that of pure silica aerogel. 실리카-벤젠 에어로겔은 균일하고 정렬된 네트워크 기공 구조, 개선된 기계적 특성을 갖도록 합성되었다. 실리카 에어로겔의 기계적 특성을 향상시키기 위해 유기물을 첨가하는 것이 일반적인 방법이지만, 기공 특성이 유-무기 상분리 현상으로 인해 감소한다. 본 연구에서는 실리카 기반 에어로겔의 기공 특성을 유지하면서 동시에 기계적 물성을 높이기 위해 간단하고 저렴한 방법을 사용하였다. 기공 및 기계적 특성에 대한 하이드록실 결합수의 영향을 연구하기 위해 두가지 유형의 벤젠 브리지 전구체를 사용하였다. 다공성 실리카 에어로겔은 간단하고 비용-효율적이며 무공해인 졸-겔방법으로 제조되었다. 최종적으로 제조된 실리카-벤젠 에어로겔은 추가적인 silylating reagents없이 우수한 기공 특성, 높은비 표면적(1,326 m2/g), 다공성 구조 및 소수성(>140°)을 가졌다. 일부 샘플(2T4)의 경우 기계적 강도는 순수 실리카 에어로겔의 5 배 이상을 보였다.