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采用单辊旋淬法制备了Cu50Zr42Al8,Cu46 Zr47-xAl7Yx(x=2,5),Cu43Zr42AlsAg7和Cu43Zr42Al8Ag5 Y2非晶合金薄带,利用X射线衍射和差示扫描量热分析研究了合金样品的玻璃形成能力和热稳定性.结果表明,在Cu50Zr42Al8中添加适量的Ag、Y后使得非晶合金的短程有序结构发生改变.合金Cu46Zr47-xAl7Yx(x=2,5)的过冷液相区宽度ΔTx分别比Cu50 Zr42 Al8增加了19K、30K,约化玻璃转变温度Trg从0.565分别增加到0.579和0.566,参数γ从0.402分别增加到0.418和0.420,说明Y的添加提高了非晶合金的热稳定性和玻璃形成能力.合金Cu43Zr42 Al8Ag7和Cu43Zr42Al8Ag5Y2与Cu50Zr42Al8相比,约化玻璃转变温度Trg及参数γ均有了明显的提高,达到了0.619、0.416和0.609、0.411,表明Ag的添加、Ag和Y的同时添加均提高了Cu - Zr -Al系非晶合金的玻璃形成能力,但Ag的效果更加显著. 相似文献
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以Y56Al24Co20非晶合金为基础合金系,用廉价Zr替代部分高价Y,通过单辊急冷法成功地制备出Y56-x-ZrxAl24Co20(x=5,10,15)非晶合金;通过X射线衍射(XRD)和差示扫描量热法(DSC)研究其非晶形成能力和热稳定性.结果表明,随Zr含量增加,合金的非晶形成能力提高,但当Zr含量超过10%(摩尔分数)时,其非晶形成能力反而降低;Y46Zr10Al24Co20具有最大的非晶形成能力和良好的热稳定性.以上结果均从组元个数、原子半径、混合热和电负性的角度进行了实验论证. 相似文献
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通过对非晶合金Cu_(17)Ni_8Sn_8P_7的初淬和退火态进行DSC分析(差动扫描量热分析),得到多种加热速度下的玻璃化温度及晶化温度,用Henderson提出的变温动力学方法计算了非晶合金在晶化开始温度和蜂值温度下的转变激活能,并确定了非晶合金玻璃转变激活能的方法。最后讨论了转变激活能和温度的关系,并估算了晶化过程中成核和生长的激活能。 相似文献
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向以Zr80Co15Al5为基体的非晶合金中添加微量铜和镍,利用铜模吸铸法和半固态处理工艺制备棒状(Zr0.88Cu0.12)95-2x Al5(NiCu)x(x=1.5、2.5、3.5)非晶合金。利用SEM、XRD和光学显微镜(OM)分析研究了半固态处理工艺对非晶合金的微观组织结构、玻璃形成能力及断口形貌的影响。结果表明,在半固态处理工艺基础上对Zr80Co15Al5添加微量铜和镍后有较好的晶体形成能力。 相似文献
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利用单辊急冷法制备Y56-xZrxA124Co20(x=0,5,10)非晶合金,研究Zr含量对该非晶合金的形成能力及热稳定性的影响.研究结果表明,添加元素Zr可以提高Y56A124Co20合金的非晶形成能力和热稳定性,而且随着Zr含量增加,合金的非晶形成能力提高.通过示差扫描量热法(DSC)研究了Y56A124Co20和Y46Zr10A124Co20的晶化动力学,前者的玻璃转变激活能和晶化激活能分别为366.5 KJ/mol和259.7 KJ/mol,后者的玻璃转变激活能和晶化激活能分别为415.6 KJ/mol和319.5KJ/mol,从理论上说明添加元素Zr可以改善Y56A124Co20合金的非晶形成能力和热稳定性. 相似文献
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Al-Co-Y合金系非晶的形成及其晶化过程 总被引:1,自引:0,他引:1
利用熔体快淬法制备出了Al92-xCo8Yx(x=4,6,8,9,10)薄带,采用X射线衍射(XRD)和扫描电镜(SEM)进行结构分析,示差扫描量热仪(DSC)进行热稳定性分析。研究了Y的加入对合金的非晶形成能力的影响以及Al84Co8Y8合金薄带等温退火的晶化过程。结果表明:当Y的原子分数为8%时,合金系的非晶形成能力最好;非晶态Al84Co8Y8合金的晶化过程分为3个阶段进行,退火过程中的组织结构转变为:非晶合金→非晶基体+初晶α-Al+少量未知亚稳相→α-Al相+未知亚稳相+Al9Co2→α-Al相+Al9Co2相+Al3Y相。 相似文献
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采用水冷铜模吸铸法制备出部分晶化的Ni55Nb30Sn5Ti5Zr5和Ni55Nb30Sn5Zr10块体非晶合金,并利用X射线衍射(XRD)分析和示差扫描量热仪分析(DSC)对合金的相组成及热物性参数进行了测量分析。采用极化曲线法研究合金在不同溶液中的腐蚀行为,并利用失重法测定合金在10%HCl溶液中的腐蚀速率,对腐蚀后的显微形貌及表面成分进行了扫描电镜(SEM)观察和能谱分析(EDS)。结果表明,Ni55Nb30Sn5Ti5Zr5合金比Ni55Nb30Sn5Zr10合金具有更宽的过冷液相区和更好的抗腐蚀性能。随着合金晶化相的增多,合金抗腐蚀性能降低。Ti元素的加入可在合金表面形成氧化钛的保护膜,从而使合金的抗腐蚀性能提高。 相似文献
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Crystallization of Amorphous Alloys 总被引:1,自引:0,他引:1
A. L. Greer 《Metallurgical and Materials Transactions A》1996,27(3):549-555
Crystallization of amorphous alloys is compared with conventional solidification of melts. Taking account of the temperature
dependence of crystal nucleation and growth rates, the links between the two processes are explored. The fundamentals of nucleation
and growth kinetics in amorphous alloys are reviewed. It is shown that the crystallization of amorphous alloys can be exploited
(1) to obtain ultrafine grained microstructures with useful properties and (2) to elucidate nucleation mechanisms in conventional
grain-refining practice.
This article is based on a presentation made at the “Analysis and Modeling of Solidification” symposium as part of the 1994
Fall meeting of TMS in Rosemont, Illinois, October 2–6, 1994, under the auspices of the TMS Solidification Committee. 相似文献
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Rapidly solidified Al89Ni6La5 ribbons were obtained by induction melting and ejecting the melt onto a rotating Cu wheel in an Ar atmosphere. The ribbons
were investigated by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), transmission electron microscopy
(TEM), microindentation, and nanoindentation techniques. The XRD and TEM studies revealed that the ribbon was fully amorphous;
however, DSC did not show any glass transition. The alloy undergoes two stages of crystallization. The growth of fcc-Al is
responsible for the first stage, and precipitation of Al3Ni and Al11La3 is responsible for the second stage of crystallization. Microhardness of ribbons in the as-melt-spun, partially, and fully
devitrified conditions was examined and subsequently correlated with evolved microstructure. Significant improvement in hardness
was observed, with the progress of primary nanocrystallization, due to the effective barrier to shear band by a hard La-rich
shell around the fcc-Al nanocrystals and enrichment of the remaining amorphous matrix by the solute elements. The pile up
of materials in the form of semicircular shear bands was observed around all the indentations. During nanoindentation, it
was observed that hardness and modulus values were initially increased and then decreased. The reasons for such observation
were also discussed. 相似文献
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用不同加热速度下差热扫描量热卡计研究了Fe79.5P18-xCxCu0.Mo0.5Si1.5非晶材料的晶化动力学。实验结果表明:磷Fe(b.c.c)起始晶化温度升高。对Fe79P18-xCxCu0.5Mo0.5Si1.5非晶材料,随着碳含量增多含量的减少,DSC曲线出现双峰,并且两峰峰值温差ΔT=TP2-Tp1加宽。 相似文献
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采用示差热分析(DSC)研究了旋铸急冷法在大气环境中制备出的Co68.5Fe4Si10B17.5非晶合金的非等温晶化的动力学行为。研究发现:在连续加热条件下,随升温速率的加快,合金的特征温度Tg,Tx,Tp均向高温区移动。当分别采用晶化开始温度和峰值温度时,所得非晶合金的激活能并不是稳定值。用Doyle-Ozawa方法计算出的激活能值比Kissinger法计算出的激活能值要大。非晶态Co68.5Fe4Si10B17.5合金的晶化百分比与退火温度和退火时间的关系曲线均呈S型。随加热速度的增加,非晶合金的晶化百分比与温度的关系曲线向高温处移动。 相似文献
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Casey Smith Shravana Katakam Soumya Nag Y. R. Zhang J. Y. Law Raju V. Ramanujan Narendra B. Dahotre Rajarshi Banerjee 《Metallurgical and Materials Transactions A》2014,45(7):2998-3009
The role of the solute elements, copper, and niobium, on the different stages of de-vitrification or crystallization of two amorphous soft magnetic alloys, Fe73.5Si13.5B9Nb3Cu1, also referred to as FINEMET, and a Fe76.5Si13.5B9Cu1 alloy, a model composition without Nb, has been investigated in detail by coupling atom probe tomography and transmission electron microscopy. The effects of copper clustering and niobium pile-up at the propagating interface between the α-Fe3Si nanocrystals and the amorphous matrix, on the nucleation and growth kinetics have been addressed. The results demonstrate that while Cu clustering takes place in both alloys in the early stages, the added presence of Nb in FINEMET severely restricts the diffusivity of solute elements such as Cu, Si, and B. Therefore, the kinetics of solute partitioning and mobility of the nanocrystal/amorphous matrix interface is substantially slower in FINEMET as compared to the Fe76.5Si13.5B9Cu1 alloy. Consequently, the presence of Nb limits the growth rate of the α-Fe3Si nanocrystals in FINEMET and results in the activation of a larger no. of nucleation sites, leading to a substantially more refined microstructure as compared to the Fe76.5Si13.5B9Cu1 alloy. 相似文献
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Co77.5Si13.5B9非晶合金的制备与非等温晶化动力学效应 总被引:3,自引:2,他引:1
采用旋铸急冷工艺在大气环境中制备出了Co77.5Si13.5B9非晶合金带材。X射线衍射(XRD)和透射电镜(TEM)分析表明样品为完全非晶。用差热分析仪测量了非晶薄带的热稳定性参数Tg,Txi,Tpi,加热速度分别为5,10,15,35,55,75,95 K.min^-1。分析了合金的非等温晶化动力学行为,计算了两个析晶峰的晶化表观激活能。研究发现:不同升温速率的DTA曲线表明非晶合金的晶化过程为两步晶化,在连续加热条件下,随升温速率的加快,Co77.5Si13.5B9非晶合金的特征温度Tg,Txi,Tpi均向高温区移动,说明其玻璃转变和晶化行为均有动力学效应。当分别采用晶化开始温度和两个峰值温度时,所得非晶合金的激活能并不是一稳定值。Ozawa方法计算出的激活能值与Kissinger法计算出的结果是一致的。非晶态Co77.5Si13.5B9合金的晶化百分比与退火温度和退火时间的关系曲线均呈S型曲线,随加热速度的增加,非晶合金的晶化百分比与温度的关系曲线向高温处移动,晶化百分比与时间的关系曲线则向时间缩短的方向移动。 相似文献
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To study the thermal expansion of amorphous Fe Si B alloys, the amorphous Fe78Si9B13 and Fe735Nb3 Cu1Si135B9 and their crystallized alloys were detected using thermal dilatometer. The results indicate that at the same temperature, the relative length change (ΔL/L0) values of the two Fe based amorphous alloys decrease with increasing heating rate, but those of their crystallized alloys show an opposite trend. It is concluded that the effect of heating rate on the ΔL/L0 of amorphous and crystallized alloys is related to free volume and defects, respectively. 相似文献
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Ying Shen Xiu-Cheng Zheng Guang-Ping Zheng 《Metallurgical and Materials Transactions A》2011,42(1):211-218
Microstructure with microsized amorphous grains is found in thick-film Co-Fe-P amorphous alloys prepared by electrodeposition.
The amorphous alloys exhibit different structure, mechanical properties, and crystallization behaviors compared with those
of homogeneous amorphous alloys, e.g., bulk metallic glasses. The mechanical properties of these microstructured amorphous alloys are characterized by tensile
tests, dynamic mechanical analysis, and micro- and nanoindentations. Using a differential scanning calorimeter, the activation
energy of the crystallization process of the microstructured amorphous alloy is measured and is found to depend on its microstructure. 相似文献