共查询到20条相似文献,搜索用时 62 毫秒
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目的 研究TiB2.TiAl3/2024Al复合材料多向锻造金属流动行为,以及锻造温度、锻造道次对复合材料再结晶行为及基体晶粒尺寸的影响。方法 将TiB2.TiAl3/2024Al复合材料的本构模型及再结晶动力学模型导入Deform-3D有限元模拟软件中,建立复合材料多向锻造的数值仿真模型。通过数值仿真方法分析锻造温度和锻造道次对复合材料多向锻造组织的影响规律。结果 多向锻造变形过程中,剧烈塑性变形和动态再结晶主要分布在材料试样内部的呈“X”形状的区域,单次下压最大等效应变为1.42。锻造1道次时,锻造温度从350 ℃升至500 ℃,再结晶体积分数从65.0%升至69.7%,平均晶粒尺寸由350 ℃的24.6 μm降至500 ℃的21.5 μm。在450 ℃锻造温度下,1道次锻造后,再结晶体积分数为69.2%,平均晶粒尺寸由铸态的45.0 μm减小到21.9 μm;2道次锻造后再结晶体积分数为89.5%,平均晶粒尺寸为16.3 μm;3道次锻造后坯料的再结晶体积分数为96.1%,平均晶粒尺寸为14.3 μm。与试验结果比较可知,模拟结果准确可靠。结论 提高锻造温度和增大锻造道次可以促进试样发生动态再结晶,从而达到细化晶粒的目的。 相似文献
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MB2镁合金变形组织性能研究 总被引:4,自引:1,他引:4
为了探讨镁合金铸造组织在较低温度下变形时对组织性能的影响,采用现代冶金分析和测试方法,研究了MB2镁合金铸棒在不同变形温度和变形程度下组织演变过程和再结晶行为,并对各变形条件下试样进行拉伸实验.结果表明,通过挤压变形及动态再结晶,可以显著细化铸造MB2合金的晶粒,其尺寸可由铸态的约100 μm减少到5μm;随变形温度的升高,MB2合金的抗拉强度下降,达到一定温度后,趋于稳定;在相同的变形程度下,随着变形温度的升高,晶粒有长大的趋势. 相似文献
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通过对热轧的ZK61镁合金板材试样分别进行不同温度和不同保温时间的退火实验,利用金相显微镜(OM)观察显微组织,对晶粒尺寸进行分析和处理,并建立数学模型,系统研究了轧制ZK61镁合金的晶粒长大行为。研究结果表明,晶粒尺寸随着退火温度的升高与退火时间的延长而粗化,退火温度对晶粒长大的影响比退火时间的影响明显。对于ZK61镁合金在250~450℃温度区间的晶粒长大过程,其晶粒尺寸与加热时间的关系可用Beck方程D~n-D_0~n=kt描述,其中k=k_0exp[-Q_g/(RT)]。计算可得晶粒长大指数n为3.5,长大激活能Qg为45kJ/mol。 相似文献
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为满足大型LEICA金相热台系统对金相试样的特殊要求,设计制作了磨制试样的专用夹具。该夹具的制作不仅提高了试样的制作效率,而且解决了试样在磨制过程中的污染问题,从而使金相试样在不同温度下的相变图像显示更加清晰,试验结果更加准确。 相似文献
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热模拟圆柱形压缩试样上金相观测点的选取 总被引:5,自引:0,他引:5
利用ABAQUS有限元分析软件,模拟了热模拟试验中圆柱形压缩试样上的应变分布以及试样鼓形的变化。通过比较试样的鼓形,确定了在Gleeble3800热模拟试验机进行圆柱形试样压缩试验时压头与试样间的摩擦系数,根据此结果模拟计算得到压缩试样上进行金相观测的合适位置。 相似文献
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A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils. 相似文献
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The end of over unit products of more than Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits beer wine yellow wine fruit syrup wine others cover over % of the national top-branded liquor products.…… 《中国标准化(英文版)》2008,25(1):30
The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.…… 相似文献
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Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster. 相似文献
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N.A. Odintsova N.V. Ageenko K.V. Kiselev N.M. Sanina E.Y. Kostetsky 《International Journal of Refrigeration》2006,29(3):387
We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes. 相似文献
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David R. Smith F. R. Fickett 《Journal of research of the National Institute of Standards and Technology》1995,100(2):119-171
Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability. 相似文献
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Fco. Javier Franco Pérez Marc Gener Moret 《Materials and Manufacturing Processes》2017,32(7-8):876-884
ABSTRACTThe production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials. 相似文献
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As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion. 相似文献
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Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting. 相似文献
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TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure. 相似文献
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R. Owsiński S. Kamiński M. Szymaniec A. Niesłony T. Łagoda 《Materialwissenschaft und Werkstofftechnik》2015,46(10):1059-1067
The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase. 相似文献