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1.
纳米复合永磁材料的原始淬态组织对最终的显微组织结构和磁性有着决定性的影响,为了弄清其影响规律,研究了成分为Pr7Fe88B5的双相纳米复合永磁材料的淬态组织在回火时相转变的过程和晶化后的组织结构及磁性。X射线谱和Mossbauer谱的研究结果表明,在不同辊速下制得的快淬带样品的组织结构是不同的。原始淬态组织的不同导致回火时的不同相变过程,它们分别是(1)非晶相Am Pr2Fe14B α-Fe→Pr2Fe14B α-Fe;(2)非晶相Am α-Fe→(Am)′ α-Fe→α-Fe 1:7相+Pr2Fe14B→Pr2Fe14B α-Fe;(3)Am→Am′+α-Fe→1:7相+α-Fe→Pr2Fe14B α-Fe。虽然样品最终的相组成均为α-Fe和Pr2Fe14B,但不同原始态的样品晶化后的显微组织和磁性并不同相同。  相似文献   

2.
采用单辊快淬法制备Fe75Nb8B15Zr2非晶合金,对该非晶合金进行不同温度的等温退火,研究其晶化过程及结构变化.利用示差热分析仪(DTA)确定样品的退火温度,利用X射线衍射(XRD)测试其相结构.结果表明:Fe75Nb8B15Zr2合金在快淬速率为38m/s时呈完全非晶状态,随着退火温度的升高,α-Fe相逐渐析出,并伴随有硼化物(Fe3B和Fe2B)析出.Fe75Nb8B15Zr2非晶合金的晶化过程:非晶→非晶+α-Fe→α-Fe+Fe3B→α-Fe+Fe3B+Fe2B.  相似文献   

3.
纳米复合永磁材料的原始淬态组织对最终的显微组织结构和磁性有着决定性的影响,为了弄清其影响规律,研究了成分为Pr7Fe88B5的双相纳米复合永磁材料的淬态组织在回火时相转变的过程和晶化后的组织结构及磁性.X射线谱和Mossbauer谱的研究结果表明,在不同辊速下制得的快淬带样品的组织结构是不同的.原始淬态组织的不同导致回火时的不同相变过程,它们分别是(1)非晶相Am+Pr2Fe14B+α-Fe→Pr2Fe14B+α-Fe;(2)非晶相Am+α-Fe→(Am)′+α-Fe→α-Fe+1:7相+Pr2Fe14B→Pr2Fe14B+α-Fe;(3)Am→Am′+α-Fe→1:7相+α-Fe→Pr2Fe14B+α-Fe.虽然样品最终的相组成均为α-Fe和Pr2Fe14B,但不同原始态的样品晶化后的显微组织和磁性并不相同.  相似文献   

4.
CeO2含量对MgO-Al2O3-SiO2系玻璃结构和晶化特性的影响   总被引:3,自引:1,他引:3  
采用熔融法制备了不同氧化铈含量的MgO-Al2O3-SiO2系玻璃;采用差热分析方法研究了氧化铈含量对MgO-Al2O3-SiO2系玻璃转变温度和晶化峰值温度的影响以及谊系玻璃的晶化机理;采用红外光谱技术研究了氧化铈对玻璃结构的影响,并验证了玻璃的差热分析结果;采用X射线粉末衍射分析方法对经900℃热处理后不同氧化铈含量的玻璃样品进行了晶相分析。研究结果表明:加入少量的氧化铈(w(CeO2)≤4%)能降低玻璃的转变温度,有利于玻璃粉体的烧结和促进α-堇青石相的形成,但氧化铈含量超过4%时将起相反作用;玻璃的析晶难易程度和析晶峰温度的高低不存在相互对应关系;玻璃的析晶活化能随着氧化铈含量的增加而增加;所有玻璃的晶化为表面晶化。  相似文献   

5.
SiO2-Al2O3-ZnO-SrO-La2O3为基本成分制备了微晶玻璃样品,在750℃下不同时间热处理。用微波微扰法测量其微波介电性能,结合扫描电镜和X射线衍射分析了其晶相。结果表明,随保温时间的延长,样品的主晶相经历了SrZrSi2O7→SrAl2Si2O8→新玻璃相La2ZrTiO7的变化。SrAl2Si2O8相是亚稳过渡相。反应生成的新玻璃相La2ZrTiO7的Q值高达1800,温度系数约为+500×10^-6/℃。  相似文献   

6.
对所选的CaO-Al2O3-SiO2系统中4个组分的微晶玻璃样品的部分重要性能进行了测试,利用XRD、IR、SEM等仪器对样品的析晶形貌和结构进行了分析;应用齿科材料相关的性能测试标准,考察了其用作齿科全瓷冠修复材料的可能性。实验发现:样品经微晶化处理后,试样中主要析出了钙铝方柱石和α-硅灰石晶相,这些晶相的析出提高了玻璃的性能。G3样品的化学稳定性等物化性能指标均达到或超过了天然牙齿相应的性能.  相似文献   

7.
本文用差动热分析方法研究了二种不同急冷速率下形成的非晶 CO_(75)B_(25)合金样品晶化过程的特征,结果表明,该材料的晶化通过多形性转变直接形成正交 CO_3B 相.冷速高的样品较冷速低的样品晶化温度有明显提高,但晶化激活能却没有多大差别.所得 Avrami 指数表明晶化过程接近于淬入晶核的匀速生长过程.文中将所得结果和别的作者的结果进行了比较和讨论.  相似文献   

8.
该文研究了聚丙烯在纯化过程中的结晶结构,发现次晶聚丙烯样品经己烷抽提后,变成了α晶聚丙烯;α晶聚丙烯样品经己烷抽提后,结晶变好,结晶度有所提高.  相似文献   

9.
用快冷法制备了Fe91-xZr5BxNb4(FZBN)合金,当5≤x≤30时,样品为非晶态,研究了B含量对非晶合金晶化的影响,当x≤20时,FZBN非晶以一次品化的模式晶化;当20〈x〈30时,以共晶模式晶化;当x=30时,以多晶模式晶化,晶化产物为具有立方结构的Fe-Zr-B-Nb合金相,随着x的增加,FZBN非晶的晶化温度(Tx)增加,当x〉20时,由于晶化模式的改变,Tx突然迅速增加。  相似文献   

10.
通过测量不同温度的穆斯保尔谱和热磁曲线,研究非晶态Fe76.6Si4.9B18.5合金颗粒的结构和磁性随温度的变化.从室温到673K时,颗粒基本保持非晶态结构,但有少量弛豫发生,表现为铁磁性;在723K时呈现顺磁性。得到其非晶态居里点是720K,长时间保持723K时,样品有晶化现象,但在晶化温度735K以下,主体仍为非晶态结构;773K时,颗粒已完全转变为晶态结构,主要包括Fe2B和Fe3Si及a-Fe等晶相,呈现铁磁性;在815K和873K时,铁磁性晶态相混合物中,伴有顺磁相FeSi出现;1173K时,合金颗粒已在Fe2B和a-Fe的居里温度以上,表现为顺磁性.由谱中还可看出,制备出非晶态原料中Fe2B和a-Fe相的比例与由非晶态晶化得到的晶态中的比例明显不同.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

19.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

20.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

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