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 共查询到19条相似文献,搜索用时 358 毫秒
1.
用葛摆测量了a-PdCuSi合金的内耗-温度曲线,证明在该合金的Tg和Tx温度附近有两个内耗峰P1和P2.P2峰是与非晶晶化有关的内耗峰,而P1峰可能是弛豫型的内耗峰,分析了倒扭摆和Collette摆的灵敏度,阐述了这责任中摆不适用于测量a-PdCuSi类合金的内耗峰。  相似文献   

2.
报道了新开发的纳米晶Fe73.5Cu1Nb2V1Si13.5B9合金的综合软磁性能。新合金的高频铁损水平为:P3/100k=510kW·m-3,P2/200k=748kW·m-3,P2/500k=3671kW·m-3和P0.5/1000k=871kW·m-3。新合金的铁损比早期开发的纳米晶Fe-Cu-Nb-Si-B合金的低且明显低于优良的功率Mn-Zn铁氧体H7c4的铁损。对铁损与频率和幅值磁通密度的关系进行了分析。也报道了新合金在若干方面的实际应用。  相似文献   

3.
Cu和Nb对非晶态Fe—Si—B合金等温晶化过程的影响   总被引:2,自引:0,他引:2  
采用示差扫描量热卡计(DSCI)得到了非晶态Fe-Si-B合金加入Cu和Nb后的等温晶化放热曲线,结合X射线衍射(XRD)分析,明确了Cu和Nb在形成纳米α-Fe(Si)晶体相时的作用。此外,非晶态Fe76.5Si13.5B9Cu1Nb3等温化的α-Fe(Si)放热峰呈明显的非对称形状。  相似文献   

4.
在含有Cu~(2+)和Sn~(2+)的溶液中加入NaH_2PO_4为还原剂可以获得金黄色的Cu-Sn-P合金镀层。研究了镀液中Cu~(2+)/Sn~(2+)浓度比、络合剂、催化剂、还原剂和酸度对镀层沉积速度和镀层中Cu/Sn比的影响,同时还测量了镀层的孔隙率和耐蚀性。结果表明,镀层色泽与镀层中铜含量有关,Cu-Sn-P合金层的耐蚀性取决于镀层中磷的含量。  相似文献   

5.
对Fe73.5Cu1Mo3Si13.5B9微晶软磁合金的结构及其对合金磁性的影响了研究,结果表明,在最佳磁性能下,晶相点阵常数a=0.2843nm,相当于Fe(Si)固溶体中含Si%(mol/mol):18-20,体积百分数V=74.8%,晶粒尺寸D=14.6nm;残余非晶层厚度δ=1.23nm;当T退火≥560℃时明显有Fe-B化合物析出。Fe73.5Cu1Mo3Si13.5B9合金的磁性不仅与  相似文献   

6.
用XRD法研究了退火Fe73.5Cu1Nb3Si13.5B9合金中α-Fe(Si)晶化相的有序化过程,结果表明,Fe73.5Cu1Nb3Si13.5B9非晶合金在490℃,1h退火后,α-Fe(Si)晶化相是具有DO3结构的有序相,有序畴为球形,直径为7.0nm,它随退炎温度的升颃是长大,在590℃退火后达10.9nm,与α-Fe(Si)的尺寸相当,此时α-Fe(Si)的有序度为0.8,在850℃  相似文献   

7.
用差热分析(DTA),结合X射线衍射(XRD)研究了Sm8Fe83Si2C5Cu0.5Nb1.5非晶合金的晶化动力学。结果表明:温度在0 ̄1000℃范围内,该合金的晶化相为α-Fe和Sm2(FeSi)17Cx,α-Fe相的晶化表观激活能力349.53kJ/mol,Sm2(FeSi)17Cx的晶化表观激活能力316.19kJ/mol,两相在晶化初期激活能量小,随晶化量(xc)的增加激活能增大,当α-  相似文献   

8.
在KDP、TGS中,Tc附近分别观测到两个内耗(Q-1)和介电损耗(D)峰,在LNPP中观测到相应的两个内耗峰,P1峰起源于二级相变的涨落效应,而P2与畴有关.考虑到Tc附近序参量以及由之而引起的畴界密度和畴界运动的粘滞系数随温度的显著变化,计算了与畴界运动有关的内耗和介电损耗,并和实验结果进行了比较.在弛豫铁电体PMN—PT中,Tc以下也观测到相应于P2峰的内耗和介电损耗峰,考虑到畴界运动和其它一些因素,对该峰进行了讨论  相似文献   

9.
金属/YSZ多晶陶瓷电极交流阻抗特性   总被引:8,自引:3,他引:5  
本文测量了以Y2O3稳定的ZrO2(YSZ)电池:Air,M(pt、Au、Pd-Ag)|YSZ)|M(pt、Au、Pd-Ag),Air在250~500°C、12Hz~100KHz之间的交流阻抗.从作出阻抗谱分析,计算了YSZ多品陶瓷的晶内、晶界电阻及其对温度的依从性.晶界阻抗半圆的特征频率和温度的关系同样服从于Arrhenius公式.比较了Pt、Au和Pd-Ag电极在YSZ氧化物电解质上的极化特性,并对氧通过各个电极扩散的电极过程中氧浓度-扩散率的积CO作了计算.  相似文献   

10.
本文采用了不同温度下两次烧结的新方法,制备了系列X射线影象存储材料BaF_xCl_(2-x):Eu ̄(2+)(x=0.90,0.95,1.00,1.05,1.101.15)。通过改变F/Cl比值,研究了在X射线辐照后BaF_xCl_(2-x):Eu ̄(2+)的热释发光性质,给出了热释发光峰的温度与缺陷种类的关系。最后,我们研究了BaF_xCl_(2-x):Eu ̄(2+)的光激励发光性质,给出了F/Cl比值与光激励发光强度的关系。  相似文献   

11.
Al-3.3Fe-10.7Si alloy has been experimentally made with spray deposition technology. The internal friction of the alloy which was directly associated with the microstructures under spray deposited, extruted and heat treated conditions has been investigated using a low frequency inverted torsion pendulum over the temperature region of 10–300 °C. An internal friction peak was observed in the temperature range 50–250 °C in the present alloy. The Q-1 peak decreased after extruted and in subsequent to the earliness of isothermal annealing, which was found to be directly attributed to the precipitation of FeAl2 and Al– Fe– Si intermetallics from the supersaturated aluminium alloy matrix. We suggest that the internal friction peak in the alloy originates from grain boundary relaxation, but the grain boundary relaxation can also be affected by FeAl2 and Al– Fe– Si intermetallics at the grain boundaries, which will impede grain boundary sliding.  相似文献   

12.
采用低频倒置扭摆内耗仪对组分为 Pb(Zr0.7Ti0.3)O3 (PZT73)和 Pb(Zr0.3Ti0.7)O3 (PZT37) 的两种陶瓷的内耗 Q-1及振动频率的平方 f 2(正比于材料的剪切模量 G)与温度的关系进行了 测定。在纯三角相的 PZT73陶瓷中发现两个内耗峰。高温内耗峰 PM起源于材料的顺电-铁 电相变 ,低温内耗峰 P1本质上是一个宽化的 Debye峰,可归因于氧空位作用下的畴壁振荡弛豫。 对纯四方相的 PZT37陶瓷,除了 P1和 PM峰外,在 P1与 PM峰之间另有内耗峰 P2,这与 900畴附 近的氧空位团簇的弛豫有关 ,其特征可用描述强关联系统的关联态模型( Coupling model)描述。  相似文献   

13.
The damping properties of Zn–22 wt.% Al alloys without and with Sc (0.55 wt.%) and Zr (0.26 wt.%) were investigated. The internal friction of the determined by the microstructure has been measured in terms of logarithmic decrement (δ) using a low frequency inverted torsion pendulum over the temperature region of 10–230 °C. An internal friction peak was separately observed at about 218 °C in the Zn–Al alloy and at about 195 °C in Zn–Al–Sc–Zr alloy. The shift of the δ peak was found to be directly attributed to the precipitation of Al3(Sc, Zr) phases from the alloy matrix. We consider that the both internal friction peak in the alloy originates from grain boundary (GB) relaxation, but the grain boundary relaxation can also be affected by Al–Sc–Zr intermetallics at the grain boundaries, which will impede grain boundary sliding. In addition, Al–Sc–Zr intermetallics at the grain boundaries can pin grain boundaries, and inhibit the growth of grains in aging, which increases the damping stability of Zn–22 wt.% Al alloy.  相似文献   

14.
The mechanical relaxation in binary, ternary, quaternary, and quitary bulk metallic glasses with widely different glass-forming ability, or the critical cooling rate, has been studied. A single-roller melt-spinning apparatus was used for preparing thin specimens. The internal friction Q−1 and the oscillation frequency f of the specimens were measured using an inverted torsion pendulum with the free decay method. The measurements were performed from room temperature, through the glass transition temperature Tg, up to the crystallization temperature Tx. As the temperature is increased, the background Q−1 increases, and peaks can usually be seen near Tg and Tx. The shear modulus, which is proportional to f2, is changed near the Q−1 peak. The experimental data are presented and overall features of the results are discussed.  相似文献   

15.
In the last 50 years several studies have been made to understand the relaxation mechanisms of the heavy interstitial atoms present in transition metals and their alloys. Internal friction measurements have been carried out in a Nb–Ti alloy containing 3.1 at.% of Ti produced by the Materials Department of Chemical Engineering Faculty of Lorena (Brazil), with several quantities of oxygen in solid solution using a torsion pendulum. These measurements have been performed by a torsion pendulum in the temperature range from 300 to 700 K with an oscillation frequency between 0.5 and 10 Hz. The experimental results show complex internal friction spectra that have been resolved, into a series of Debye peaks corresponding to different interactions. For each relaxation process it was possible to obtain the height and temperature of the peak, the activation energy and the relaxation time of the process.  相似文献   

16.
Measurements of internal friction as a function of temperature were carried out in samples of niobium containing different amounts of interstitial solutes (oxygen and nitrogen) and one sample of niobium containing initially only nitrogen as interstitial solute. The experimental spectra of internal friction as a function of temperature were obtained with a torsion pendulum of the inverted Kê-type and resolved, using the method of successive subtraction, into a series of constituent Debye peaks corresponding to different interactions. For each relaxation process it was possible to obtain the height (Qmax−1) and temperature (Tp) of the peak, the activation energy (E) and the relaxation time (t0). The height, shape and temperature of these peaks depend on the concentration of interstitial elements. The observed peaks were associated with matrix-interstitial (Nb---O, Nb---N) and interstitial–interstitial (O---N) interaction processes.  相似文献   

17.
Effects of deep cryogenic treatment (DCT) on the internal friction (IF) in high-carbon alloy steel are investigated. The temperature dependent internal friction (TDIF) of the quenched and DCT treated samples were measured in an inversed torsion pendulum with high vacuum by using free decay method. The TDIF of quenched sample is decomposed into four peaks: P1 at 342 K, P2 at 443 K, P3 at 492 K and P4 at 580 K. Peak P1 is attributed to the relaxation associated with the reorientation of interstitial solute atoms in metals under the application of oscillatory stress. Peak P2 is related to the carbides precipitation. Peak P3 is considered as the Snoek-Kê-Köster (SKK) peak, which is caused by both dislocations interaction and interstitial atoms decorating these dislocations. Peak P4 is attributed to retained austenite transformation basing on the peak disappearing while the samples carried out DCT treating.  相似文献   

18.
用内耗技术研究La0.7Pb0.3MnO3巨磁电阻材料   总被引:1,自引:0,他引:1  
用低频扭摆法在多功能内耗仪上测量了巨磁电阻材料La0.7Pb0.3MnO3(LPMO)的温度内耗谱和弹性模量。结果表明,内耗峰位与测量频率无关,并且峰高与频率成反比,弹性模量在对应的内耗峰处有明显的转折,内耗峰表现为相变峰的特征,结合电阻和磁化率的测试,解释了内耗和电阻-温度曲线的双峰现象,高温内耗峰和高温电阻峰与居里温度有很好的对应,来源于顺磁半导体向铁磁金属的转变,低温内耗峰和磁化率的单调下降来源于铁磁相分离过程。而较大的低温电阻峰部分来源于相分离过程。  相似文献   

19.
The internal friction and relative elastic modulus of polypropylene (PP) filled with nanometer-scale calcium carbonate (nm-CaCO3) particles in different contents (0, 4, 7, and 15 vol.%) are measured in the temperature range 150–400 K with a torsion pendulum. The peak associated with the glass transition and a small peak (′ peak) associated with the pre-melting process in crystalline parts of PP was observed around 290 and 370 K, respectively. At temperatures lower than 270 K, no peaks were observed. With increasing content of nm-CaCO3 particles, the apparent activation energy of the peak decreases, and after passing a minimum of 4.7 eV at 4 vol.% of nm-CaCO3, it increases. In contrary to this behavior, the peak temperature has a maximum of 289 K at the same filler fraction. Correspondingly, the highest tensile and flexural strength of PP were obtained around this content. These observations may be understood through the influences of fillers on the degree of crystallization of PP and on the mobility of molecules of PP.  相似文献   

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