共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
3.
4.
采用拓展连续模型预测大尺寸2024铝合金半连铸铸锭的Cu和Mg元素的偏析分布。该模型耦合宏观传输方程与近似相图的微观偏析模型来预测铸锭宏观偏析,并探讨传输机制对宏观偏析形成的影响。模拟结果表明,从铸锭中心到铸锭表面Cu元素和Mg元素具有相似的偏析分布,铸锭中心与紧邻铸锭表面的区域呈现负偏析分布,而铸锭表面和铸锭1/2半径处显示一定程度低估的正偏析分布,并详细分析导致此结果的原因。此外,在三元铝合金中由于第三组元Mg元素的影响,Cu元素的偏析相较铝铜二元合金中Cu元素的偏析要轻。计算结果表明预测值与文献实验结果基本一致。 相似文献
5.
6.
本文研究了我厂试制的GH698合金个别试样中温塑性偏低的原因。对试样的组织、大γ′相不均匀性、元素偏析、夹杂物及晶界状态等与实物进行了对比。研究结果表明,大γ′相分布不均匀是合金中Al、Ti偏析所致。夹杂物多且沿轧向呈条带分布,大颗粒呈网状或骨架状,个别Nb(C,N)夹杂中含有氧,还存在有高Zn、S、Mg的夹杂。这些都影响了合金的中温塑性。本文也对加入微量Mg后,合金的组织、Mg的分布,对断口形貌的改善进行了详细对比分析。 相似文献
7.
8.
通过扫描电镜(SEM)观察、能谱(EDS)以及X射线衍射(XRD)分析,对3104铝合金易拉罐成品罐体早期失效的断口处第二相和夹杂物进行了表征,并通过对合金原始铸锭中第二相的研究,系统地分析了缺陷形成的原因。结果表明,铸锭和缺陷断口上均分布有大量粗大的(FeMn)Al6、(AlFeMnSi)四元相和以氧化物夹杂为主的粗大夹杂物。这些粗大相和夹杂物是导致罐体开裂的主要原因,其来源于合金的熔炼和铸造过程。通过分析,提出了防止或减少粗大化合物和夹杂物的相应措施。 相似文献
9.
在探讨连续铸造铸锭中的区域偏析问题时,一般利用正常生产铸锭的凝固方案。根据这种情况制定了下述专用术语:当组份聚集在铸锭最后的凝固区段时,这种降低合金凝固开始温度的组份分布,称为正偏析或者正常偏析。当这种组份聚集在铸锭初始凝固区段时, 相似文献
10.
典型β型钛合金元素Cu,Fe和Cr的偏析规律 总被引:1,自引:0,他引:1
通过对Ti-2.5Cu,Ti-3Fe,Ti-3Cr,Ti-13Cu-1Al,Ti-6Al-1.7Fe几种合金铸锭成分的对比研究,建立了典型β钛合金元素的偏析模式。对Ti-2.5Cu,Ti-3Fe,Ti-3Cr合金铸锭的对比可知,Cu和Fe元素的偏析程度大,Cr元素的偏析程度小;对Ti-2.5Cu和Ti-13Cu-1Al合金铸锭的对比可知,Cu元素在2种合金铸锭中的偏析均比较明显,Cu含量越高,偏析程度越大;Cu元素在2种合金铸锭的晶界有截然不同的偏析方式,Cu元素在Ti-13Cu-1Al的晶界富集而在Ti-2.5Cu的晶界贫化。对Ti-3Fe和Ti-6Al-1.7Fe合金铸锭的对比可知,Fe元素在2种合金铸锭中的偏析均比较明显,Fe含量越高,偏析程度越严重;Fe元素在2种合金铸锭的晶界均贫化。 相似文献
11.
12.
利用动态内耗方法测定了两种不同纯度Ta箔经电解充氢处理后在100—400K温度范围内的内耗值(Q~(-1)),并根据Gorsky原理计算了氢在Ta中的扩散系数。实验结果表明,在T>250K和T<180K的温度区间内氢的扩散系数D服从Arrhenius关系,同时计算了扩散常数D_0和激活能U。最后讨论了氢浓度和其它杂质对氢的扩散系数的影响。 相似文献
13.
We report on the theoretical and experimental investigations about the Ta-hydride formation depending on the temperature for recycling of Ta scraps. The structural investigations based on scanning electron microscope and X-ray diffraction (XRD) showed that the amount of hydrogen incorporated into the Ta matrix varied with hydridation temperature. The XRD measurement showed that the H/Ta mole ratio in Ta-hydride increased with increasing the hydridation temperature up to 700 °C and then decreased with increasing the temperature furthermore. Depending on the hydridation temperature, various phase of Ta-hydride, such as TaH0.93 and Ta2H were formed and this hydride process was verified by thermodynamic analysis. 相似文献
14.
钽的CVD动力学规律及显微组织 总被引:2,自引:0,他引:2
简述氢气还原氯化钽化学气相沉积钽(CVD)的主要原理,研究氯化、氯气流量、氢气流量和沉积温度4个参数对沉积速率及沉积层显微组织的影响。结果表明:氯化温度对沉积速率的影响最小,沉积温度的影响最大;显微组织由小晶粒区和柱状晶区组成,沉积参数改变,柱状晶晶粒大小发生变化。 相似文献
15.
H. Okamoto 《Journal of Phase Equilibria and Diffusion》2006,27(2):199-199
16.
S. V. Babu A. Jindal Y. Li 《JOM Journal of the Minerals, Metals and Materials Society》2001,53(6):50-52
As device dimensions continue to shrink, multilevel (>8) interconnects are required to efficiently implement complex logic
device designs in a single silicon chip. When the number of metal interconnect levels increases, the available depth-of-focus
budget of lithographic tools imposes stringent planarity requirements that can only be met currently by chemical-mechanical
planarization (CMP). Improved speed and performance are extracted from such devices by switching to copper from Al/Cu as the
interconnect metal and to lower dielectric constant inner layers. Use of copper also requires the simultaneous introduction
of diffusion-barrier/adhesion-promotion layers of tantalum or TaN. This paper reviews some of the recent advances in the fundamental
understanding of the interplay between the mechanical and chemical components of the material-removal process during CMP of
copper and tantalum films. The emphasis will be on the role of different process variables in slurries containing silica or
alumina abrasives in hydrogen peroxide/glycine solutions.
For more information, contact S.V. Babu, Clarkson University, Center for Advanced Materials Processing & Department of Chemical
Engineering, Clarkson University Box 5705, Potsdam, New York 13699-5705; (315) 268-3999; fax (315) 268-6654; e-mail babu@clarkson.edu. 相似文献
17.
1.IntroductionDuringthepasttwodecadestherehasbeensignificalltprogressinthefieldofsurfacetreatmentforreducingwearincoolextrusiondiesteel.Metalionimplantationhasseveraldistinctadvantagesoverothertechniquesforthesurfacemodificationofmaterials.FOrmodifyingwearresistancesofmetals,thesignificanteffectsusuallyinvolvehighdoseionimplantation.Themajorlimitationofimplantationwithmetallicionshasbeenthelongprocessingtimeduetosmallbeamcurrefltofconventionalimplanters.Metalvaporvacuumarc(MEVVA)ionsourceca… 相似文献
18.
19.
S. Mato G. Alcala G. E. Thompson P. Skeldon K. Shimizu H. Habazaki T. Quance M. J. Graham D. Masheder 《Corrosion Science》2003,45(12):2881-2892
The behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammonium pentaborate electrolyte has been examined by transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloys are amorphous and featureless and develop at high current efficiency with respective formation ratios of 1.67, 1.60 and 1.55 nm V−1. Anodic oxidation of the alloys proceeds without significant enrichment of iron in the alloy in the vicinity of the alloy/film interface and without oxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similar concentrations of iron. The higher migration rate of iron species relative to that of tantalum ions leads to the formation of an outer iron-rich layer at the film surface. 相似文献
20.
采用Ta层作为过渡层,通过双辉等离子渗金属(DGPSA)与射频磁控溅射(RFMS)辅助直流脉冲磁控溅射技术(DCPMS)制备TiAlN/Ta复合涂层。借助掠入射XRD、SEM、AFM、纳米压痕、划痕以及摩擦磨损测试了不同工艺制备的Ta过渡层对复合涂层的相结构、表面(截面)形貌、硬度、结合力、韧性和摩擦磨损性能的影响。结果表明,TiAlN复合涂层在高偏压作用下结构致密,RFMS技术制备的Ta过渡层为柱状晶结构,复合涂层表面粗糙度较小,硬度较大而磨损稳定性和耐磨性较差;而DGPSA技术制备的Ta过渡层为纳米晶结构,复合涂层表面粗糙度较大,硬度降低但磨损稳定性与耐磨性都增强。对比发现,通过DGPSA技术制备Ta过渡层使得TiAlN/Ta复合涂层的结合力与韧性大幅度提高。 相似文献