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The effects of deformation parameters and cooling rates on the aging behavior of AZ80+0.4%Ce

Journal of Magnesium and Alloys 2024年第2期12卷 639-658页

作者： Yongbiao Yang Jinxuan Guo Cuiying Wang Ting Yan Zhang Wenxuan Jiang Zhimin Zhang Qiang Wang Guojun Li Jun Wang College of Materials Science and Engineering North University of ChinaLane 3Xueyuan RoadTaiyuanShanxiChina030051 State Key Laboratory of Advanced Stainless Steel Materials Taiyuan Iron Steel(Group)Co.Ltd.Taiyuan 030003China Technology Center Shanxi Taigang Stainless Steel Co.Ltd.Taiyuan 030003China

The extruded AZ80+0.4%Ce magnesium alloy was twisted in the temperature range of 300-380℃by using a Gleeble 3500 thermal simulation test machine with a torsion *** deformed cylindrical specimens were cooled at a cooling rate of 10℃/s or 0.1℃/s,respectively,and aged at 170℃.The microstructure analysis results showed that the grain size decreased with increasing specimen radial position from center(SRPC),and that the strong initial basal texture of the extruded magnesium alloy was *** continuous and discontinuous dynamic recrystallization mechanisms were involved in contributing to the grain refinement for all specimens *** a novel extension twinning induced dynamic recrystallization mechanism was proposed for specimen deformed at 300℃.For the specimens deformed at 300℃and 340℃followed by a slow cooling rate(0.1℃/s),precipitates of various shapes(β-Mg_(17)Al_(12)),with the dominant precipitates being on the grains boundaries,appeared on the surface *** specimen deformed at 380℃,lamellar precipitates(LPS)in the interiors of the grains were *** aging,the LPS still dominated for specimens twisted at 380℃;however,the LPS gradually decreased with decreasing deformation temperatures from 380℃to 300℃.Dynamically precipitatedβ,especially those decorating the grain boundaries,changed the competition pictures for the LPS and precipitates of other shapes after ***,LPS dominated the areas for the center section of the specimens after aging regardless of deformation *** temperature deformation with high SRPC followed by rapid cooling rate increased the micro hardness of the alloy after aging due to refined grain,reduced precipitates size,decreased lamellar spacing as well as strain hardening.

关键词： AZ80+0.4%Ce magnesium alloy Hot torsion Deformation parameters Cooling rate Aging micro hardness

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Impingement capability of high-pressure submerged water jet: Numerical prediction and experimental verification

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Journal of Central South University 2015年第10期22卷 3712-3721页

作者：刘海霞邵启明康灿龚辰 School of Material Science and Engineering Jiangsu University School of Energy and Power Engineering Jiangsu University

At jet pressures ranging from 80 to 120 MPa, submerged water jets are investigated by numerical simulation and experiment. Numerical simulation enables a systematic analysis of major flow parameters such as jet velocity, turbulent kinetic energy as well as void fraction of cavitation. Experiments facilitate an objective assessment of surface morphology, micro hardness and surface roughness of the impinged samples. A comparison is implemented between submerged and non-submerged water jets. The results show that submerged water jet is characterized by low velocity magnitudes relative to non-submerged water jet at the same jet pressure. Shear effect serves as a key factor underlying the inception of cavitation in submerged water jet stream. Predicted annular shape of cavity zone is substantiated by local height distributions associated with experimentally obtained footprints. As jet pressure increases, joint contribution of jet kinetic energy and cavitation is demonstrated. While for non-submerged water jet, impingement force stems exclusively from flow velocity.

关键词： submerged water jet cavitation shear effect impingement test micro hardness surface morphology

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Relationship between mechanical properties and grain size of AZ80 at 350℃ under different strain rates

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Transactions of Nonferrous Metals Society of China 2010年第B07期20卷 584-588页

作者：权国政宋涛周一俊王凤彪周杰 College of Materials Science and Engineering Chongqing University

The dynamic recrystallization refinement of magnesium alloy AZ80 by compression tests was studied,and its effect on the mechanical properties was *** is observed that the microstructure of the as-cast billet with grain size of 240μm becomes refined to about 120,110,94 and 50μm after upsetting at 350℃ under strain rates of 0.01,0.1,1 and 10 s -1 *** changes in the mechanical properties according to grain size show that yield strength significantly decreases with grain size increasing,while strain hardening exponent and micro hardness increase very ***,the grain size vs strain rate and change in Vickers micro hardness according to the various strain rates show that grain size and micro hardness decrease with strain rate increasing.

关键词： magnesium alloy refinement compression softening behaviour micro hardness

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Effect of Different Bleaching Applications on the Surface Properties and Staining Susceptibility of Dental Composites

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Journal of Wuhan University of Technology(Materials Science) 2016年第3期31卷 677-683页

作者： Pinlar Gul Osman Tolga Harorli Nilgün Ak Mustafa Gündogdu Department of Restorative Dentistry Faculty of DentistryAtaturk University25240-ErzurumTurkey Department of Restorative Dentistry Faculty of DentistryAkdeniz University07058-AntalyaTurkey Department of Prosthetic Dentistry Faculty of Dentistry Ataturk University25240-ErzurumTurkey

The aim of this study was to investigate the effects of two bleaching systems on micro hardness, surface roughness and color stability of two novel dental composites. Ormocer based restorative Admira and nano-filled composite Clearfil Majesty Esthetic were bleached with 10% carbamide peroxide （Opalescence PF） or 35% hydrogen peroxide （Beyond Max 5） and subsequently immersed in four different staining solutions （coffee, tea, red wine, and cola）. Distilled water was used as a control. Color measurements were performed with a spectrophotometer. Vickers micro hardness and roughness data were analyzed with two- way analysis of variance for repeated measures. The analysis of variance was used to compare the color change values. Duncan＇s multiple comparison test was applied to compare the results （a = 5%）. AE~＂ values over 3.3 were considered clinically unacceptable. micro hardness and surface roughness values of the tested composites were decreased significantly after bleaching applications. Red wine and tea storage caused perceptible discolorations in the composite resin materials after 30 days of 3-hour immersion. Home or office bleaching applications can affect the surface properties of resin composites and accelerate the staining process.

关键词： composite resin bleaching surface roughness micro hardness discoloration

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Metal-Ceramic Smart Composite in Ti(C,N)-Ni-Mo-W System

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Journal of Electronics Cooling and Thermal Control 2016年第2期6卷 42-51页

作者： Z. Kovziridze N. Nizharadze G. Tabatadze E. Nikoleishvili M. Mshvildadze Department of Chemical and Biological Technologies Georgian Technical University Tbilisi Georgia

Goal: Low wolfram-containing cutting composite was obtained by fusion of titanium carbonitride and high melting temperature binding metallic phase. Method: The composite was obtained via compaction and further sintering in vacuum furnace at 1600°C under 10-3 Pa pressure. Phase analysis was performed on X-ray apparatus “DRON-3”;microstructure was determined by electron microscope NANOLAB-7, microhardness by MUCKE-mark microhardness meter;relative resistance of cutters was evaluated at similar modes of cutting according to distances they passed;experiments were carried out on turning lathe. Results: Physical-mechanical characteristics of the obtained composite are: σbend, = 1000 - 1150 MPa, σbend1000°C = 600 MPa, HV = 14 GPa;HV1000°C = 6.5 GPa. High speeds of cutting and high temperatures resistance of cutters made by the obtained composites exceeds 1.5 - 2-folds that of cutters made of the known BK8 and KNT20 hard alloys. Conclusion: Its application is recommended in hot steel treatment by cutting, for removal of the so-called burrs, as well as in steel treatment by cutting during pure and semi-pure operations. It can also be used in jet engines, chemical industry apparatuses, electric-vacuum devices, in industry of responsible details of rockets, nuclear reactors, flying apparatuses.

关键词： Metal-Ceramic Composite Cutting Material High-Temperature Heatproof micro hardness

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Synthesis, Growth and Characterization of Sodium Mixed Cadmium Oxalate Crystals

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Journal of Crystallization Process and Technology 2016年第2期6卷 11-20页

作者： F. Daisy Selasteen S. Alfred Cecil Raj A. Alagappa Moses F. Emalda Prince R. Esther Getsy R. Elakkiya Department of Physics Bishop Heber College Tiruchirappalli India Department of Physics St. Joseph’s College Tiruchirappalli India Department of Environmental Sciences Bishop Heber College Tiruchirappalli India

The newly synthesized CdNa2?2C2O4?2H2O crystals having a size of 0.30 × 0.25 × 0.20 mm3 were grown by the single-diffusion reaction method in the silica gel medium at 28?C temperature. The crystalline nature of crystals was determined in 20 days by 1) varying the concentrations of the feed solutions and the gel pH level, 2) changing the specific gravity of the feed solution, and 3) changing the gel aging period. The crystals were characterized by using the methods such as powder X-ray diffraction, FTIR, UV, SEM-EDAX, TGA/DTA, and micro-hardness test. The structure of as-grown crystals was determined by the powder crystal XRD patterns. FTIR & SEM-EDAX spectral analyses were used to confirm the presence of the required functional groups of as grown crystals. UV absorption spectrum, the absorption peaks at 224.64 nanometer, determined the energy gap. TGA/DTA thermo gram was used to detect the thermal stability of sodium mixed cadmium oxalate dihydrate crystals. The present grown crystals were brittle and also plastic in nature was identified by Vickers micro-hardness test.

关键词： CdNa2?2C2O4?2H2O Crystal Growth XRD FTIR UV TGA/DTA SEM-EDAX micro hardness

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