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用透射电子显微分析,金相分析及扫描俄歇微探针研究了50B钢淬火后回火是硼碳化物的形成及其动力学,确认硼碳化物Fe23(B,C)6和Fe3(C,B)。Fe23(B,C)6在马氏体分解时析出于Fe3C之后,析出温度在490℃或更高,析出的动力学曲线为“C”形的下半部,Fe3(C,B)则在较长时间回火时由Fe3C转变而成,其形成的学曲线是以700℃和550℃为鼻尖“ε”形。 相似文献
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氟碳铈矿热分解行为的研究 总被引:10,自引:0,他引:10
采用XRD法分析了不同温度下氟碳铈矿焙烧分解产物的组成,探讨了氟碳铈矿的热分解过程。试验结果表明氟碳铈矿的热分解是分步进行的。首先(Ce,La)CO3F分解成(Ce,La)OF;升高焙烧温度,(Ce,La)OF发生相分解,生成Ce0.75Nd0.25O1.875和(Ce,Pr)La2O3F3两相;随着焙烧温度的继续升高,(Ce,Pr)La2O3F3可分解为LaF3、Ce2O3、PrO1.83等相。焙烧过程中Ce3+、Pr3+氧化为四价,没有明显的脱氟行为。 相似文献
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用金相、透射电子显微镜、电子探针与扫描电镜分析研究得出超低碳Cr26-Ni28-Mo5-Cu3-Nb0.35不锈钢铸态组织中含有σ相,经850 ̄1120℃热处理均可形成σ相,包括(Fe-Cr)σ相,(Fe-Mo)σ相和(Cr-Ni-Si)σ相,850℃左右有M6C型碳化物和NbC析出。该钢经1150℃2h水冷固溶处理后,具有优良的耐腐蚀性能。 相似文献
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采用循环伏安法研究了LaF_3-LiF二元熔体及添加La_2(CO_3)_3的LaF_3~LiF熔体中,920~950℃下,La ̄(3+)在石墨电极上还原的阴极过程。结果表明:在LaF_3-LiF熔体中,电位在-0.85V左右(相对于石墨参比电极),La ̄(3-)离子在阴极还原析出;在添加La_2(CO_3)_3,的LaF_3-LiF三元熔体中,La(CO_3)_3,分解为La_2O_3,La_2O_3首先电解,然后LaF_3电解,均在阴极上析出镧。镧离子的电化学反应是简单的一步反应,即La ̄(3+)+3e→La。 相似文献
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用火焰原子吸收光谱法(FAAS)测定硬质合金混合料及碳化物在制粉工艺中,由球磨过程带入杂质Fe,Co,Ni的变化可知,使用硬质合金球磨简及球,Co的增量是Fe的3-7倍。使用不锈钢球磨筒时,Fe的增量为0.10%-0.40%。破碎碳化物时,若使用不锈钢球磨筒和硬质合金球,研磨时间超过48h后,各元素的增量分别为:Fe>0.40%,Co>0.2%,Ni>0.1%。 相似文献
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下贝氏体碳化物形态及来源 总被引:1,自引:0,他引:1
用TEM观察了Fe-1.08C-3.95Cr合金一贝氏体碳化物(θ)的形态,发现θ呈棒状或楔状。实测碳化物的主轴方向近似与「100」或「010」平行,楔根源于贝氏体铁互体-奥氏体界面,或部分深入铁素体内部而形成在相界面钉扎的特殊形态。提出铁素体(α)可能按激发形核-扩散台阶(SNLG)机制长大,θ和α竞争长大,α的形成过程决定了θ的形态及分布。 相似文献
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饱和氯化镁卤水中锂与金属络合阴离子共萃取效应的研究 总被引:2,自引:0,他引:2
研究了在饱和氯化镁盐湖卤水中,锂与各种络合阴离子的共萃取效应,结果表明,以FeCl3最佳。对锂与铁络合阴离子共萃取相关因素──总Cl-浓度、酸度、Fe/Li进行了讨论,保持原始水相FeCl3不致水解的最低酸度和高Cl-浓度,FeCl3与Cl-形成铁络阴离子,与Li+以LiFeCl4络合物形式共萃取进入有机相。化学法分析平衡有机相组成表明,所有阳离子摩尔浓度的总值与Fe3+摩尔浓度相等,而Cl-摩尔浓度与Fe3+摩尔浓度比值为4,证明了以络酸HfeCl4和络酸盐Me(FeC14)n(n为金属阳离子价数)的共萃取机理。 相似文献
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热处理对钢结硬质合金TLMW50中复式碳化物形态与分布的影响 总被引:1,自引:0,他引:1
利用SEM对烧结态和热处理态钢结硬质合金TWLM50微观组织中复式碳化物形态与分布进行研究。结果表明:烧结态钢结硬质合金TLMW50微观组织中主要复式碳化物Fe3W3C、Fe2W2C相形状基本呈现长条状,宽约10—20μm之间,颗粒长度可达10~60μm之间,且复式碳化物的晶粒上还有细小的三角状二次碳化物析出。经过1050℃淬火,250℃回火复式碳化物颗粒的棱角有所钝化,条形颗粒明显减少。二次碳化物析出数量明显减少,大部分二次碳化物溶于或与初生复式碳化物发生反应,形成复式碳化物,且随机分布在初生复式碳化物上。热处理导致钢结硬质合金TWLM50硬度提高到65HRC,耐磨性显著提高。 相似文献
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Sunghak Lee Chang Gil Lee Dongil Kwon Sung-Ho Park Nack J. Kim 《Metallurgical and Materials Transactions A》1996,27(5):1241-1250
Microscopic examination and microstructural analysis of vertical cracking phenomena in deep-drawn cups of hot-rolled SG295
steel strips were carried out in this study. Microvoids initiated preferentially at grain-boundary carbides were observed
to form intergranular cracks. These grain-boundary car-bides were identified as (Fe,Mn)3C carbides. The morphology of carbides was varied with processing variables,e.g., killing method and coiling temperature. In the Al-killed steels, the carbide shape tends to change from film type to bulk
type, which may be beneficial to elongation and consequently formability. In addition, as the coiling temperature increased,
the amount of banded pearlite structures and bulk-type carbides increased. These findings suggest that the deep drawability
can be improved by modifying the carbide morphology in the microstructures. 相似文献
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T. P. Hou Y. Li Y. D. Zhang K. M. Wu 《Metallurgical and Materials Transactions A》2014,45(5):2553-2561
The effect of a 12-T high magnetic field on alloy carbide precipitation in an Fe-C-Mo alloy during tempering at an intermediate temperature was investigated. Thin foils and carbon extraction replicas of the treated specimens were examined by transmission electron microscopy (TEM). The results show that the applied high field effectively promoted the precipitation of (Fe,Mo)6C alloy carbide. The concentration of Fe atom in Fe6?x Mo x C carbide is increased whereas that of Mo atom decreased when the high magnetic field was applied. However, the high magnetic field almost had no detectable influence on the atom concentration in (Fe,Mo)2C and (Fe,Mo)3C carbides. First principle calculations have been performed to calculate the magnetic moment per iron atom of the carbides to explore the origin of the effect of the magnetic field. The influence of the high magnetic field on the precipitation behaviors of alloy carbides was closely related to the magnetic moment of (Fe,Mo)2C, (Fe,Mo)3C, and (Fe,Mo)6C. The magnetic field promotes the formation of the carbides with high total magnetic moment. The effect of the high magnetic field on the substitutional solute atom (Fe and Mo) concentration change in the three alloy carbides was attributed to their magnetization differences per Fe atom. 相似文献
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Zhixing Guo Ji Xiong Mei Yang Siqin Bi 《Metallurgical and Materials Transactions B》2009,40(6):871-876
Both hard CVD coatings deposited on cemented carbides and the use of innovative binders for Co-bonded cemented carbide attract
worldwide interest. In this article, ISO grade P30 cemented carbides are prepared with Fe Ni and Co binder, and adherent Ti(C,N)
coatings are deposited on all the substrates by moderate-temperature chemical vapor deposition (MTCVD). The microstructure
and properties of the cemented carbides before and after coating process are studied. The results show that Ti(C,N) coatings
on all the substrate show compact and well-developed columnar structures, and high adhesion strength can be achieved. 相似文献
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为了改善M2高速钢共晶碳化物的分布,本文利用小凝固试样变质的方法研究了Ti,N和Mg对M2高速钢凝固组织和硬度的影响。试验结果表明,加入Ti或Ti-N后,共晶碳化物形态和分布有很大改善,而加入Ti-N后对凝固组织有轻微的细化作用,但只添加Ti不补碳时,钢的淬火硬度和回火硬度均下降;加入适量的Mg可以使片状的M2C型共晶碳化物转为鱼骨状的M6C型共晶碳化物,使其分布有所改善,Ti和Mg复合加入可以明 相似文献
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Xiaodan Zhang Wei Liu Dale Sun Youguo Li 《Metallurgical and Materials Transactions A》2007,38(3):499-505
The transformation of carbides with austenization time of a high speed steel (HSS) roll material, manufactured by a centrifugal
casting method, has been studied. The correlation between wear resistance and the type, morphology, volume fraction, and distribution
of the carbides has also been investigated. Microstructural observations, X-ray diffraction (XRD) analysis, hardness measurements,
and energy dispersive spectroscopy (EDS) have been used to characterize the carbides. The type and volume fraction of carbides
were found to change with austenizing time. During austenization, the transformation of the M3C carbides can be postulated as M3C + γ-Fe → M2C, with much finer nodular and rodlike MC carbides also forming through a solid-state transformation. The M2C carbide decomposes as M2C + γ-Fe → MC + M7C3 + M6C. The decomposed carbide substantially maintains a platelike shape until the end of decomposition. The most important finding
of this study is that austenization results in changes in the type, morphology, volume fraction, and distribution of carbides
and that it can be controlled to produced a homogeneous distribution of hard carbides, resulting in an improvement in the
wear resistance of HSS rolls. This finding may be of great use for the industrial production of HSS rolls. 相似文献