淬火硼钢回火时硼碳化物的形成及其动力学

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。     

氟碳铈矿热分解行为的研究

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。     

超低碳Cr26－Ni28－Mo5－Cu3－Nb0．35铸造不锈钢的组织和耐蚀性能

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。     

超低碳Cr26—Ni28—Mo5—Cu3—Nb0.35铸造不锈钢的组织和耐蚀性能

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。     

在氟盐体系中镧离子阴极过程的研究

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。     

用火焰原子吸收光谱法研究球磨过程中带入杂质Fe,Co,Ni的含量变化

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％。     

正火12Cr1MoV钢回火脆化的冷速敏感性

采用示波冲击试验和高分辨透射电子显微分析技术，研究了回火冷却方式对正火１２Ｃｒ１ＭｏＶ钢回火脆化的影响。结果表明，该钢存在两个不同的回火冷速敏感性温度区间；高于６４０℃回火，铁素体基体中沉淀析出碳化物以ＶＣ类型为主，回火脆性没有明显的冷速舔生，低于６４０℃回火，基体中沉淀析出的碳化物以Ｆｅ３Ｃ类型为主，回火脆化具有明显的冷速敏感性和可逆性。     

喷射沉积Al-Si-Fe-Cu-Mg合金中的相组成

对喷射沉积快速凝固Ａｌ－Ｓｉ－Ｆｅ－Ｃｕ－Ｍｇ合金的相组成进行了分析。结果表明：合金中含有α－Ａｌ、β－Ｓｉ、δ（ＦｅＳｉ２Ａｌ４）、Ａｌ８Ｓｉ６Ｍｇ３Ｆｅ和β（Ｆｅ２Ｓｉ２Ａｌ９）等相;初晶硅相呈颗粒状,共晶硅相和δ（ＦｅＳｉ２Ａｌ４）呈细小的片状,Ａｌ８Ｓｉ６Ｍｇ３Ｆｅ相呈细小的颗粒状;经Ｔ６工艺热处理后,新析出Ａｌ２Ｃｕ相,Ａｌ８Ｓｉ６Ｍｇ３Ｆｅ相数量增加,少量δ（ＦｅＳｉ２Ａｌ４）转化为β（Ｆｅ２Ｓｉ２Ａｌ９）。     

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

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。     

下贝氏体碳化物形态及来源

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。     

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

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。     

合金碳化物M23 C6的磁性及磁致磁性

摘要：利用第一性原理研究了碳化物M23C6（M=Fe,Cr）的晶胞结构、磁矩和态密度,并结合魏氏分子场理论分析了磁场作用下一些碳化物的磁致磁性。结果显示：Fe20Cr3C6碳化物中的Fe3和Fe4原子连接组成稳定的晶格框架,Cr1、Cr2和C原子位于框架中心;Fe20Cr3C6的磁性主要来源于Fe和Cr原子的3d轨道贡献,并且贡献的方向相反,Fe23C6和Fe20Cr3C6中存在sp和pd轨道杂化;Fe20Cr3C6中具有负磁矩的Cr原子,削弱了紧邻Fe原子以及碳化物整体的磁矩;磁场作用下,碳化物的铁磁态相区扩大,磁矩增大。最终发现,碳化物M23C6在中温相变时依旧保持着较强的磁性,且磁场诱导磁性增加,可以预测,强磁场能够改变碳化物M23C6的析出稳定性。上述工作揭示了强磁场和温度耦合作用下复杂碳化物的结构、磁性及其稳定性影响的内在关联机制。     

Analysis and prevention of vertical cracking phenomena during deep drawing of hot- rolled sg295 steel strips

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.     

Magnetic Field-Induced Precipitation Behaviors of Alloy Carbides M2C,M3C,and M6C in a Molybdenum-Containing Steel

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 Fe_6?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.     

时效超低碳低密度钢中碳化物的形成与控制

摘要：采用SEM、EBSD、TEM等试验方法对时效超低碳低密度钢中碳化物的形成机制与控制进行了研究。结果表明,试验钢在热处理后存在粗大的碳化物析出相（Fe3C、TiC）。试验钢中Fe3C碳化物随时效温度提高发生长大,Fe3C析出相与位错的作用为绕过机制,其与时效后细晶强化的共同作用使得试验钢强度大幅增加。试验钢中TiC为微米级析出相,呈方形或三角片状分布,其直径随时效温度的升高而减少,形状由不规则趋向球形。TiC与基体间存在高密度位错使得试验钢在变形过程中形成位错堆积,从而增加了基体变形的难度,导致试验钢塑性降低。     

Ti,N,Mg对M2高速钢凝固组织和硬度的影响

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     

Adherent Ti(C,N) Coatings on Cemented Carbide Substrates with Fe/Ni/Co Binder

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.     

合金碳化物M7C3的磁性与电子结构

摘要：合金碳化物的析出行为决定了耐热钢在中、高温条件下的服役寿命。利用Diamond软件探索了合金碳化物M7C3(M=Fe,Cr)的晶体结构,并统计了M7C3中原子间的成键情况。同时,利用第一性原理计算其在0K、0Pa条件下M7C3中各原子的磁矩和电子结构。结果表明,M7C3中的Fe、C原子沿着〈001〉方向分层排列,且Fe原子沿着〈001〉方向构成了正方形、三角形、六角环;Fe—C键的键长越长,对应Fe原子的磁矩越大;态密度分布显示M7C3的磁矩贡献主要来自于Fe原子的d轨道,Fe原子d轨道与C原子的p轨道发生了杂化,形成了共价键、离子键,且M7C3具有金属性。Cr原子的自旋极化度小于Fe原子,所以Cr原子的加入使得M7C3的磁性减小。此研究有助于拓展碳化物的应用与控制技术,为碳化物的析出强化机制提供了理论基础。     

粘结剂成分对WC－20（Fe／Co／Ni）硬质合金力学性能和显微组织的影响

用常规的粉末冶金工艺试制了四种成分的ＷＣ－２０（Ｆｅ／Ｃｏ／Ｎｉ）合金，优选粘结剂的成分及总碳量可使其力学性能最佳。着重研究了ＷＣ－２０（Ｆｅ／Ｃｏ／Ｎｉ）合金的力学性能和显微组织，发现：粘结相为李晶马氏体和奥氏体时，其主要力学性能不低于ＷＣ－２Ｃｏ；而粘结相全部为板条马氏体时，其主要力学性能低于ＷＣ－２Ｃｏ     

The Transformation of Carbides during Austenization and Its Effect on the Wear Resistance of High Speed Steel Rolls

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.