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1.
稀土对莱氏体钢共晶碳化物粒化的影响   总被引:6,自引:2,他引:4  
研究了稀土对莱氏体钢中共晶碳化物热处理粒化的影响,探讨了稀土元素的作用机制。结果表明:稀土细化了莱氏钢中奥氏体晶粒和共晶碳化物,使离异共晶数量增多,减少了Cr、Mo合金元素偏析,并使M7C3(M=Fe、Cr)碳化物中孪晶等晶格缺陷增多,从而降低碳化物的稳定性,促进了共晶碳化物的粒化动力学过程,得到良好的粒化效果。  相似文献   

2.
二次硬化马氏体时效钢中纳米级强化相的分析   总被引:1,自引:0,他引:1  
马翔 《分析化学》1996,24(12):1379-1382
本文采用电化学相分析法确定它是一种M2C型碳化物,并利用两种溶液的联合处理法克服了在碳化物间相分离时复合合金化的碳化物(Fe,Cr,Mo)2C中元素间的选择性溶出,提高了相分析的准确度。  相似文献   

3.
稀土对铸造Cr12MoV模具钢碳化物形貌及性能的影响   总被引:15,自引:3,他引:12  
研究了稀土元素对铸造Cr12MoV模具钢碳化物形貌及性能的影响。实验结果表明,稀土地M7C3型共晶碳化物有很强的变质作用,Cr12MoV模具钢铸态为粗大的网状共生共晶组织,经变质处理,共晶组织细化,离异共昌数量半多;热处理后共晶碳化物粒化且均匀分布,冲击韧性得到了明显提高,耐磨性比锻造Cr12MoV模具钢高出1倍以上。  相似文献   

4.
通过η5-R~1C_5H_4(CO)_3MNa与η~5-R~2C_5H_4(CO)_3MNa(M=Mo,W)以及η~5-R~1C_5H_4(CO)_3MoNa与η~5-R~2C_5H_4(CO)_3WNa在Fe_2(SO_4)_3醋酸水溶液作用下的交叉氧化偶联反应,合成了7个新的非对称型金属单键化合物η~5-R~1C_5H_4(CO)-3Mo─Mo(CO)_3C_5H_4R~2-η~5(R~1,R~2:C(O)Me,CO2Et),η5-R1C5N4(CO)3W─W(CO)3C5H4R2-η5(R1,R2:C(O)Me,CO2Et;H,CO2Et)和η5-R1C5H4(CO)3Mo─W(CO)3C5H4R2-η5(R1,R2:C(O)Me,H;Et,C(O)Me;C(O)Me,n-Bu;CO2Me,n-Bu).用C/N分析、IR、1HNMR和MS表征了它们的结构,并对该氧化偶联反应的特点进行了讨论.  相似文献   

5.
研究了含汞三金属化合物「η-RC5H4(CO)3M2「Hg(M=Mo,W;R=Me,Et,CO2Me,CO2Et)与锌粉的置换反应,发现当取代基R为给电子的Me和Et时底物不发生反应,而取代基R为拉电子的CO2Me和CO2Et时,则底物中的汞可被锌置我。  相似文献   

6.
1,2-双(四甲基环戊二烯基)四甲基二硅烷与正丁基锂作用生成(四甲基二硅撑)双(四甲基环戊二烯基负离子盐),后者随即与六碳基钼反应形成1,1’-(四甲基二硅撑)双(四甲基环戊二烯基铝负离子盐)-(Me2SiSiMe2)[Me4CpMo(CO)3-Li+]2( I), I与冰醋酸作用,随即分别与CCl4, NBS及I2反应,生成相应的铝卤化合物(Me2SiSiMe2)[Me4CpMo(CO)3X]2[X=Cl(1),Br(2),I(3)].I与CH3I反应,在钼原子上发生烃基化,得到产物(Me2SiSiMe2)[Me4CpMo(CO)3Me]2(4);I与单质I2直接反应,生成脱硅桥产物Me4Cp(CO)3I(5).经元素分析、 IR及1H NMR表征了化合物 1-5的结构.  相似文献   

7.
系列同三核铬、锰、铁羧酸配合物的FAB-MS研究   总被引:3,自引:3,他引:0  
进行了系列同三核羧酸配合物〔M3O(O2CR)6Py3〕X(M=Cr,Mn,Fe;R=CH3,C2H5,C6H5;X=Cl-,ClO4-;Py为吡啶)的快原子轰击质谱(FAB-MS)研究。获得了包括配位吡啶在内的完整阳离子峰。在研究其断裂规律时,主要观察到4个系列碎片离子:Ⅰ.〔M3O(O2CR)n〕+,n=6~2;Ⅱ.〔M3O(O2CR)nO〕+,n=5~1;Ⅲ.〔M2O(O2CR)n〕+,n=3~1;Ⅳ.〔M2(O2CR)n〕+,n=4~2。通过对该系列配合物质谱断裂过程的比较和分析,获得了配合物稳定性随金属离子及配体的变化如下:金属离子,Cr>Mn>Fe;桥配基,-CH3CO2>-C2H5CO2>-C6H5CO2;端配基,Py>H2O。本研究及先前的工作〔1,8〕还为某些三核铬,铁羧酸配合物在以乙炔加水或加氢为探针反应中存在活性物种:〔Cr3O(O2CR)3~4〕,〔Fe3O(O2CR)3〕和〔Fe3O-(O2CR)O〕~〔Fe3O4〕提供了佐证  相似文献   

8.
四甲基二硅桥连取代环戊二烯基配体相继与丁基锂及MC14。2THF作用,生成四甲基二硅桥连取代环戊二烯基钛和锆化合物(Me2SiSiMe2)(C5H4R)(C5H4R1)MC12「R=H,R1=t-Bu,M=Ti(1),Zr(2),Hf(3);R=H,R1=Me,M=Ti(4);R=R1=Me,M=Ti(5),Zr(6)」。通过元素分析、MS和H1NMR谱表征了化合物的分了结构,并通过X射线衍射分析  相似文献   

9.
标题化合物(Me2SiSiMe2)〔η^5-(3-Me3SiC5H3)Fe(CO)2〕2/(μ-CO)2(A)分子中的Fe-Fe键被钠汞齐还原断裂,生成相应的双铁负离子,分别与MeCOCl、PhCOCl、PhCH2Cl、ClCH2COOC2H5和Ph3SnCl进行亲核取代反应,生成在铁原子上引入相应取代基的产物(Me2SiSiMe2)〔η^5-(3-Me3SiC5H3)Fe(CO)2R〕2(R:M  相似文献   

10.
研究了含汞三金属化合物[η_5-RC_5H_4(CO)_3M]_2Hg(M=Mo,W;R=Me,Et,CO_2Me,CO_2Et)与锌粉的置换反应,发现当取代基R为给电子的Me和Et时底物不发生反应,而取代基R为拉电子的CO_2Me和CO_2Et时,则底物中的汞可被锌置换,生成带有机官能团的三金属化合物[η_5-RC_5H_4(CO)_3M]_2Zn;另外,还发现R为CO_2Et,M为Mo的产物[η_5-RC_5H_4(CO)_3M]_2Zn可在室温下被分解为相应的氯代物η_5-EtO_2CC_5H_4MoCl.  相似文献   

11.
During tempering of solute supersaturated ferrous martensite, the face‐centered cubic MC‐type carbides (M is alloy elements) such as VC and NbC phases usually co‐precipitate on crystal defects such as dislocation and take on plate‐like morphology. Over‐tempering makes the plate‐like shape change to spherical shape because of Ostwald coarsening. The coarsening process strongly correlates to the diffusion behaviors of the carbon and carbide‐forming elements, and consequently inhomogeneous compositional and structural distribution in the carbides is formed. Three‐dimensional atom probe and high‐resolution transmission electron microscopy have been proved useful methods to characterize the composition, morphology and nanostructure of the carbides that precipitate in a quench‐tempered micro‐alloyed steel. Depending on the actual affinity with C and the diffusion behavior, Si and Al are rejected from the alloy carbide, whereas Mn, V and Nb are inhomogeneously enriched in it. The morphology and structure change with the compositional redistribution. During the coarsening process of the pre‐existing plate‐like carbide, transition carbide that is semi‐coherent with ferritic matrix is formed because of the disparity in diffusion ratio of different solutes. A core–shell complex nanostructure is consequently formed in the coarsening carbide, and the core and shell are identified as V8C7 enriched in Mn, Mo and Mo2C, respectively. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

12.
碳锰洁净钢中镧和铈在晶界的行为   总被引:1,自引:0,他引:1  
应用高分辨TEM,SEM和XRD研究碳锰洁净钢中镧和铈的存在形式、分布以及在晶界的行为。研究结果表明,镧和铈在洁净钢中存在固溶态、稀土夹杂物和稀土第二相。固溶稀土偏析在晶界,洁净钢中稀土仍有净化钢液和变质夹杂的作用。适量稀土能减少S和P在晶界的偏析,净化晶界提高钢的冲击韧性。过量稀土在晶界产生有害的稀土第二相,导致性能显著降低。  相似文献   

13.
Tool steels have a large range of applications including hot and cold working of metals and injection molding of plastic or light alloys. High-speed steel (HSS) is specifically used for cutting tools and for components subjected to extreme wear conditions, because of its high strength, wear resistance, hardness, toughness, and fatigue resistance. The microstructure of HSS can be described as a metallic matrix iron composite containing a dispersion of hard and wear-resistant carbides. Specimens were manufactured experimentally from T42 powder (50–80 vol%) and mixed binder (20–50 vol%) by powder injection molding. The binders (green parts) were debound in n-hexane solution at 60 °C for 8 h and thermally debound in a mixed N2–H2 gas atmosphere for 8 h. Specimens were sintered under high vacuum (10?5 Torr) at different temperatures. When sintering was performed at 1,260 °C, the specimen sintered under high vacuum had the highest hardness (550 Hv). The carbides were smaller (1 μm) and well distributed. Grain size was 10 μm. When sintering was performed under high vacuum at temperatures above 1,280 °C the carbides changed to eutectic carbide located at grain boundaries. Grain growth was observed. Specimens sintered at other pressures had lower density and hardness than those sintered under high vacuum.  相似文献   

14.
Karp HS  Bandi WR  Melnick LM 《Talanta》1966,13(12):1679-1687
Differential thermal analysis-effluent gas analysis (DTA-EGA) techniques have been applied to the determination of specific metal carbides in residues which are isolated from steels by chemical methods. In this method, a weighed portion of sample residue is transferred to the DTA sample-holder and subjected to programmed heating in a dynamic oxygen atmosphere. When combustion of the carbide occurs, a differential temperature response is recorded over a specific temperature range. The temperature range is used as an aid in identifying the specific carbide present. The thermal conductivity of the effluent gas is recorded and the signal resulting from the presence of carbon dioxide in the effluent gas is then used for the quantitative determination of the carbide. The DTA-EGA method has been applied to several experimental steels for determination of the carbides of zirconium, vanadium or titanium individually and for the determination of vanadium and zirconium carbides in mixtures of the two. Results for these metal carbides obtained by DTA-EGA agreed within 15% with those obtained by the lengthy chemical methods. The lower limits of detection, based on the original steel sample weight, were 0.02% for the vanadium and titanium carbides and 0.01% for zirconium carbide.  相似文献   

15.
稀土变质及热处理对耐磨铸铁冲击疲劳性能的影响   总被引:5,自引:1,他引:4  
采用金相显微镜、扫描电镜观察了经冲击疲劳试验后耐磨铸铁中碳化物的形貌、疲劳裂纹的萌生与扩展,测定了稀土含量及加热温度与裂纹的长度和裂纹扩展之间的关系曲线,在此基础上探讨了稀土变质及热处理对耐磨铸铁冲击疲劳性能的影响.结果表明: 稀土能推迟裂纹萌生的时间,降低裂纹扩展速率,提高其冲击疲劳抗力.当稀土与热处理共同作用时,效果更显著.其原因主要归于网状共晶碳化物形态与分布的改变.  相似文献   

16.
This paper presents a computing procedure for the indirect assessment of the matrix composition by AAS of two-stage prepared carbide isolates. Partitioning of carbon and metallic elements between matrix and carbides has been determined. Austenitizing has caused considerable increase in Mo and Cr contents in the matrix related to dissolution of carbides of the M6C type. Tempering resulted in a decrease in contents of elements forming M23C6 secondary carbides. Changes to the Ti and Nb contents in the matrices were relatively small in specimens given various heat treatments. The matrix of annealed steel has been shown to be carbonfree, whereas the carbon content in the tempered state is high in comparison to conventional high-speed steels.  相似文献   

17.
The differences in artifacts associated with voltage-pulsed and laser-pulsed (wavelength = 532 or 355 nm) atom-probe tomographic (APT) analyses of nanoscale precipitation in a high-strength low-carbon steel are assessed using a local-electrode atom-probe tomograph. It is found that the interfacial width of nanoscale Cu precipitates increases with increasing specimen apex temperatures induced by higher laser pulse energies (0.6-2 nJ pulse(-1) at a wavelength of 532 nm). This effect is probably due to surface diffusion of Cu atoms. Increasing the specimen apex temperature by using pulse energies up to 2 nJ pulse(-1) at a wavelength of 532 nm is also found to increase the severity of the local magnification effect for nanoscale M2C metal carbide precipitates, which is indicated by a decrease of the local atomic density inside the carbides from 68 ± 6 nm(-3) (voltage pulsing) to as small as 3.5 ± 0.8 nm(-3). Methods are proposed to solve these problems based on comparisons with the results obtained from voltage-pulsed APT experiments. Essentially, application of the Cu precipitate compositions and local atomic density of M2C metal carbide precipitates measured by voltage-pulsed APT to 532 or 355 nm wavelength laser-pulsed data permits correct quantification of precipitation.  相似文献   

18.
Zusammenfassung An einem unkonventionellen Schnellarbeitsstahl vom Typ M7 (2% Wolfram, 9% Molybdän, 1% Vanadin, 1% Niob, 4% Chrom) wurde gezeigt, wie durch gezielte Kombination von Interferenzschichtmetallographie, besonderen rasterelektronenmikroskopischen Abbildungsmethoden, EDX-Analyse und Röntgenbeugungsanalyse eine sichere Identifizierung der Carbidphasen möglich ist. Die Methodenkombination gestattet die Charakterisierung der Carbidphasen und deren Änderung hinsichtlich Menge und chemischer Zusammensetzung in verschiedenen Wärmebehandlungszuständen vom Guß bis zum Härtegefüge.
Volume fractions and compositions of the carbide phases in a Nb-alloyed M7 high speed steel
Summary Volume fractions were determined by quantitative microscopy from scanning and photoelectron emission micrographs, compositions by EDX analysis in SEM. The identity of the various carbide phases was established by EDX, X-ray diffraction, SEM contrast, and by comparison with color interference microscopy. MC, M6C and M2C each occurred in several variants with different compositions and lattice constants; the relation between these phases is discussed against the background of the solidification process of the steel. The metallurgical effect of Nb is to expel most of the V, W and Mo from the MC phase; these elements are accommodated in M2C and M6C whose iron content is correspondingly reduced. Only by the combination of the methods mentioned the complete analysis of the carbide phases could be accomplished. The submicroscopic carbides involved in secondary hardening were not part of the study.


Vortrag für das 10. Kolloquium über metallkundliche Analyse, Wien, 3.–5. November 1980. -Herrn Prof. Dr. Hanns Malissa zum 60. Geburtstag gewidmet.  相似文献   

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