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The deformation behavior of ultrafine-grained AZ31 Mg alloy with varied compression directionsChou, Ying-Wen 24 August 2010 (has links)
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Mg effect on mechanical properties of ultrafine grained Al-Mg alloyproduced by friction stir processingWang, Yong-yi 23 August 2010 (has links)
Al-Mg solid solution alloys of various grain sizes were prepared by
friction stir processing (FSP). The mechanical properties and
micro-structure evolution were studied. The results show that the
mechanical properties including tensile strength and ductility are
improved by increasing Mg weight fraction. The homogeneous
deformation is enhanced by fined slip bands within the grains. On the
other hand, Dynamic strain aging or serrated flow stress has been wildly
investigated in Al-Mg alloys. Effects of strain rate and magnesium
content on dynamic strain aging are also discussed.
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Effect of local chemical composition of grain boundaries on corrosive resistance and mechanical properties of ultrafine-grained titanium alloysNokhrin, A.V., Chuvil’deev, V.N., Kopylov, V.I., Kozlova, N.A., Tabachkova, N.Yu., Likhnickiy, K.V., Gryaznov, M. Yu., Berendeev, N.N., Murashov, A.A., Chegurov, M.K. 17 September 2018 (has links)
No description available.
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Effect of mechanical activation on optimal sintering temperature of ultrafine-grained tungsten heavy alloysNokhrin, A.V., Chuvil’deev, V.N., Boldin, M.S., Sakharov, N.V., Baranov, G.V., Belov, V.Yu., Popov, A.A., Lantcev, E.A., Troshin, V.N. 17 September 2018 (has links)
No description available.
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Understanding the Micromechanism of Cyclic Loading Behavior of Ultrafine Grained AlloysShukla, Shivakant 08 1900 (has links)
In the current study, we have investigated the cyclic loading behavior of conventional as well as novel alloy system exhibiting fine and ultrafine-grained structure. While in case of conventional alloy systems (here aluminum alloy AA5024), the effect of three different grain sizes was investigated. Improvement in fatigue properties was observed with decreasing grain size. The unique microstructure produced via Friction stir processing was responsible for the improved fatigue response. Additionally, microstructures consisting of a high fraction of special boundaries within the fine and ultrafine-grained regime were also subjected to cyclic loading. The hierarchical features introduced in the eutectic high entropy alloy deflected the persistent slip bands, responsible for fatigue cracking, thus resulted in delayed crack initiation and improved fatigue life. The selective nature of fatigue was learnt in the fine grain Al0.5CoCrFeNi, where the introduction of hierarchical features did not result in improved fatigue properties. The weak links in the microstructure, while not affecting the tensile properties, got exposed during cyclic loading. Further study on the medium entropy alloy revealed the inherent reason for the improved fatigue properties. The medium entropy alloys utilized the benefit of UFG single-phase FCC matrix. The UFG matrix showed signs of transformation of FCC phase into the HCP phase during fatigue deformation and hence exhibited improved work-hardening. Alongside atomic scale transformation, stacking faults and nano-twins can also be attributed for obtained cyclic properties.
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Ultra-fine grain two-phase aluminum alloys produced by friction stir processingHsu, Chih-jing 22 January 2007 (has links)
Friction stir processing (FSP) is applied to produce particulate-reinforced aluminum matrix composites with ultrafine grained structure from elemental powder mixtures of Al-Cu, Al-Ti and Al-Si. The microstructures of the composites were characterized by the use of XRD, SEM and TEM. Microhardness, tensile and compressive tests were performed to evaluate the mechanical properties of these composites. The mechanisms of microstructure evolution in FSP and the strengthening mechanisms in these composites are discussed.
In the Al-Si system, the Si particles were broken and uniformly distributed in the stir zone by the application of multiples-pass FSP. The average size of Si particles and Al grains were refined to below ~2
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超微細粒組織を有するFe-Ni-C準安定オーステナイト合金の変態誘起塑性とマルテンサイト変態に関する研究 / Transformation-Induced Plasticity and Deformation-Induced Martensitic Transformation of Ultrafine-Grained Metastable Austenite in Fe-Ni-C Alloy陳, 帥 23 March 2015 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第18986号 / 工博第4028号 / 新制||工||1620 / 31937 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 田中 功, 教授 乾 晴行 / 学位規則第4条第1項該当
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10Ni-0.1C鋼の加工熱処理中に生じる動的相変態に関する研究 / Dynamic Ferrite Transformation Behavior in 10Ni-0.1C Steel during Thermo-Mechanically Controlled Process趙, 立佳 23 March 2015 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第18987号 / 工博第4029号 / 新制||工||1620 / 31938 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 白井 泰治, 教授 松原 英一郎 / 学位規則第4条第1項該当
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Popis únavového chování UFG Ti pro biomedicínské aplikace / Fatigue properties of UFG Ti for biomedicine applicationsDobeš, Ondřej January 2019 (has links)
Titanium is thanks to its high corrosion resistance and biocompatibility widely used in medicine. Ti alloys are used due to their superior mechanical properties instead of pure Ti for load carrying components. Ti alloys are often alloyed with elements which are toxic for human body and further increase cost of Ti products. Main focus of current development is to create pure Ti with better mechanical properties. It can be done by reducing grain size by processes based on severe plastic deformation. The aim of this work is to evaluate fatigue properties as well as fatigue crack initiation and propagation mechanism of Ti grade 2 with the ultrafine grained structure. After microstructure analysis, fatigue tests with symmetrical loading were executed. Fracture surfaces of ultrafine grained Ti grade 2 were observed after fatigue tests for identification of failure mechanism. Results were compared with those for course-grained Ti grade 2.
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Studium jemnozrnných materiálů připravovaných metodou intenzivní plastické deformace / Study of ultrafine-grained materials prepared with different methods of severe plastic deformationKrajňák, Tomáš January 2015 (has links)
Title: Study of ultrafine-grained materials prepared with different methods of severe plastic deformation Author: RNDr. Tomáš Krajňák Department: Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague Supervisor: Doc. RNDr. Kristián Máthis, PhD., Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague Abstract: Interstitial free steel with ultrafine-grained (UFG) structure was prepared by high-pressure torsion (HPT). The development of the microstructure as a function of the number of HPT turns was studied at the centre, half-radius and periphery of the HPT-processed disks by X-ray line profile analysis (XLPA), positron annihilation spectroscopy (PAS) and electron microscopy. The dislocation densities and the dislocation cell sizes determined by XLPA were found to be in good agreement with those obtained by PAS. The evolution of the dislocation density, the dislocation cell and grain sizes, the vacancy cluster size, as well as the high-angle grain boundary (HAGB) fraction was determined as a function of the equivalent strain. It was found that first the dislocation density saturated, then the dislocation cell size reached its minimum value and finally the grain size got saturated. For very high strains after the...
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