7Cr7mO2v2Si钢的回火与二次硬化

研究了７Ｃｒ７ＭｏＶ２Ｓｉ钢回火时相及组织的力学性能的变化规律，着重观察了二次硬化峰值附近碳化物的结构和形貌。结果表明，该钢的二次硬化主要是ｆｃｃ结构的Ｖ４Ｃ３及Ｍｏ２Ｃ呈圆盘状宙淀所致。     

高耐磨钢回火过程中碳化物沉淀的透射电镜研究

用透射电镜研究了三种高耐磨钢在二次硬化峰附近回火时碳化物的沉淀，结果表明：耐磨钢产生二次硬化的特殊碳化物为ＭＣ＋Ｍ２Ｃ，它们和基体间满足如下取向关系：〔１１１〕ＭＣ／／〔０１１〕α，（１１０）ＭＣ／／（１００）α；〔００１〕ＭＣ／／〔０１１〕α，（２００）ＭＣ／／（２００）α；〔０１１１〕Ｍ２Ｃ／／〔００１〕α，（２１１０）Ｍ２Ｃ／／（２００）α。在５４０℃回火时，Ｓｉ能抑制耐磨钢中Ｍ３Ｃ碳化物的     

7Cr2WMoVSi钢热处理过程的碳化物的变化

本文研究了７Ｃｒ２ＷＭｏＶＳｉ钢热处理过程的碳化物的变化，结果表明，随退火温度降低，碳化物尺寸减小，７８０～８００℃退火获得均匀细化的球化组织；加热至９４０～９８０℃奥氏体化时，Ｍ３Ｃ，Ｍ２３Ｃ６已全部溶解，仍存在Ｍ６Ｃ和较多的ＶＣ剩余碳化物，有效地阻碍了奥氏体晶粒长大，随回火温度升高，按Ｍ３Ｃ，Ｍ２３Ｃ６，Ｍ６Ｃ，ＶＣ依次沉淀析出，各类碳化物的不同析出过程，提高了钢的回火抗力。     

AlN陶瓷衬底的SIMS和XRD测量

ＡｌＮ陶恣成分怀发对于ＡｌＮ的性能具有决定性作用，用二次离子质谱（ＳＩＭＳ）和Ｘ射线衍（ＸＲＤ）对清华大学材料系电子封装用的ＡｌＮ陶瓷进行了研究。ＳＩＭＳ谱表明ＡｌＮ衬底中除Ａｌ，Ｎ以我有Ｃ，Ｏ，Ｓｉ，Ｃａ，Ｙ等元素，其中有些是表面污染。衬底的ＳＩＭＳ深度分析表明样品Ｏ，Ｃａ，Ｙ信号都很强，且分布均匀，说明样口 含有Ｙ２Ｏ３，ＣａＯ添加剂，ＡｌＮ样品的ＸＲＤ谱与ＡｌＮ的ＪＣＰＤＳ卡片对照，在测量范     

硅对抑制涂层“氧化缺口”破坏的作用

本文对比了渗铝和铝－硅涂层的高温抗氧化性能，并用金相和电子探针分析技术研究了徐层的显微组织，从而揭示出硅抑制涂层“氧化缺口”破坏的机理在于：硅降低了铝的内扩散活性，使镍的外扩散活性相对提高，使合金最外表面形成很薄的表层，从而避免了ＭＣ碳化物的直接裸露；硅促进了ＭＣ→Ｍ＿６Ｃ的转化，生成富Ｓｉ的Ｍ＿６Ｃ，从而改善了涂层中碳化物自身的抗氧化性能。     

钙钛矿型复合氧化物LaMyM1‘—yO3的氧化还原性能的研究

用ＴＰＲ、ＸＲＤ和ＸＰＳ手段研究了Ｂ位二元复合钙钛矿型复合氧化物ＬａＭｙＭ１＇－ｙＯ３（Ｍ、Ｍ＇＝Ｍｎ、Ｆｅ、Ｃｏ；ｙ＝０．１－０．１）中过渡金属离子的氧化还原性能和还原过程。ＬａＭｎＯ３和ＬａＣｏＯ３及富Ｍｎ和富Ｃｏ样品的还原分为两步：第一步对应于高价过渡金属离子的还原，且不破坏钙钛矿的骨架结构，但可使晶体的对称性及缺陷浓度发生改变；第二步还原使钙钛矿结构破坏，还原产物中出现单元氧化物和金属单质     

QRO90Supreme热作模具钢的合金碳化物对钢的热稳定性的影响

主要研究了ＱＲＯ９０Ｓｕｐｒｅｍｅ热作模具钢显生组织及其合金碳化物对钢的热稳定性的影响。结果表明：该和模具钢经淬，回火后，弥散分布在马氏体基体上的碳化物大多数是ＶＣ和（ＭｎＭｏ）２Ｃ，其余为少量的Ｍ３Ｃ合金渗本，因而其回生和热稳定性明显优于ＥＳＲＨ１３钢。     

三元系ZrO3固溶体的XPS和XRD研究

对ＣｅＯ２－ＭｇＯ－ＺｒＯ２系固溶体的ＸＰＳ和ＸＲＤ研究结果表明：在１７００℃烧结和随后的１２００℃处理过程中。Ｃｅ＾４＋被还原成Ｃ＾３＋，离子半径的差别使立方相的晶格常数增大，氧的的结合能增大，镁的结合能减小，热处理时，Ｃｅ离子在ＭｇＯ偏析后仍稳定存在于ＺｒＯ２晶格中，使立方ＺｒＯ２发生与会传统Ｍｇ－ＰＳＺ不同的分解反应：ｃ－ＺｒＯ２→ｃ′－ＺｒＯ２＋ｔ－ＺｒＯ２＋ＭｇＯ。     

回火温度对16Co14Ni10Cr2Mo钢断裂韧度和抗应力腐蚀性能的影响

研究了回火温度对１６Ｃｏ１４Ｎｉ１０Ｃｒｔ２Ｍｏ钢断裂韧度ＫＩＣ和抗应力腐蚀性能ＫＩＳＣＣ的影响。发现５１０℃以下回火ＫＩＣ和冲击值ａｋ的变化一致，都表面出回火马氏体脆性，但在回火脆性区内ＫＩＣ不降低。在二次硬化峰之前ＫＩＳＣＣ值很低，这是二次硬化钢不能在硬化峰之前回火使用的重要原因。     

碘化亚铜微晶掺杂硼硅酸盐玻璃的制备及其电致二阶非线性光学效应

采用可分相的Ｎａ２－Ａｌ２Ｏ３－Ｂ２Ｏ３－ＳｉＯ２系为基础玻璃，以ＣｕＯ／ＳｎＯ、ＮａＩ为原料，分别引入Ｃｕ＾＋、Ｉ＾－，成功地制备出ＣｕＩ微晶掺杂硼硅酸盐玻璃。通过Ｘ射线粉末衍射（ＸＲＤ）和高分辨透射电镜（ＨＲＴＥＭ）分析观察到了玻璃中的晶相及其分布；由玻璃的室温透射光谱研究了玻璃的热处理条件下光吸收性的关系。首次报道了该半导体微昌掺杂玻璃中的电致二次谱波发生，并讨论了该效应的机理。     

30Cr3Si2Mn2NiNb钢中未溶相的热力学计算及分析

采用Thermo-Calc热力学软件模拟了30Cr3Si2Mn2NiNb钢奥氏体化时平衡相的演化规律以及非平衡态相的演化规律,研究了合金元素C,Mo,Nb和V对实验钢中未溶相的影响.通过SEM,XRD对30Cr3Si2Mn2NiNb钢淬火态组织进行实验观察及分析.结果表明:常规奥氏体化处理后,钢中未溶相主要有富Nb的M...     

MC complex carbide in AISI M2 high-speed steel

MC complex carbide was observed in spray formed AISI M2 high-speed steel. This carbide was extracted from samples after austenitizing and tempering. The carbide was characterized by X-ray diffraction, X-ray fluorescence and scanning electron microscopy. The extracted MC is a type of carbide not yet reported in the open literature. It is a face centered cubic carbide with lattice parameter a = 0.417028(4) nm, very close to the VC carbide but with a totally different chemical composition. The M represents the metallic elements (at.%): 36.70 V, 19.72 Cr, 2.67 Fe, 32.31 Mo and 8.60 W.     

轧辊用高速钢中碳化物研究

本文利用扫描电镜、能谱分析对三种轧辊用高速钢的组织中碳化物进行了研究,并分析了VC形态与高速钢化学成分之间的关系。结果表明：轧辊用高速钢组织包括马氏体基体,残余奥氏体和各种类型碳化物,如粒状或小块状的MC型碳化物,网状的M7G型碳化物,鱼骨状的M6C型碳化物以及其他复合型碳化物,各种碳化物含有的合金元素以及显微硬度不同;在研究范围内（Weq≤10）,晶粒尺寸是随钨当量的升高而变小;根据V含量不同,VC会出现不同形貌进而影响高速钢性能。     

Effect of tempering on development of carbide particles in 2.7Cr-0.6Mo-0.3V steel

To study the influence of tempering conditions (823–1058 K, 9–3600 ks) on the phase transformations and changes of morphology, size and chemical composition of carbide particles in 2.7Cr-0.6Mo-0.3V steel, the methods of, electron diffraction and EDXS/STEM have been used. Three carbide types: M₃C, M₇C₃ and MC have been identified altogether, the last two of which are equilibrium ones under given conditions. Diagrams describing changes in chemical composition of carbide particles and the average size during tempering have been constructed. In the development of carbide chemical composition three stages have been recorded. The carbide particles grow continuously with the increasing of time and/or temperature of tempering.     

Selective electrochemical machining of the steel molds in hot isostatic pressing of Ti6Al4V powder

Anodic dissolution is proven to be an effective method to remove stainless steel molds from Ti6Al4V compacts obtained from powder by hot isostatic pressing. Two different working solutions were studied: 2?M NaCl and 2?M NaCl?+?0.05?M Na₂EDTA. While both were capable of removing the steel mold, the latter was also capable of removing the diffusional layer made by the intermetallic phases generated between titanium and steel during the compaction process.     

Solidification microstructures and mechanical properties of vertical centrifugal cast high speed steel

Abstract

This study was undertaken to investigate the influence of Nb and V alloying elements and manufacturing conditions on the microstructural behaviour and mechanical characteristics of HSS (high speed steel) roll manufactured by a VCC (vertical centrifugal casting) process. In the Fe - 2C - 6Cr-1.5W - 3Mo - 4V alloy, the amount of MC carbide was increased and the the amount of M₇C₃ carbide decreased with an increase in V and Nb content. In steel containing 3%Nb, primary NbC carbide was formed within the cell in the matrix. The hardness of steel containing 6.5%V but no Nb was increased a little but when 9%V was added, the hardness decreased in the specimen owing to the soft ferritic matrix. The hardness of the matrix in steel containing 1.5%Nb increased, but decreased for 3%Nb addition. In wear tests, wear loss decreased with increasing rotational wear speed.     

Numerical Simulation of Reaction—Diffusion during Carburization of HK40 Steel

Two types of carbides M23C6 and M7C3 precipitate orderly as carbon concentration in a high Cr-Ni austenitic steel increases during carburization process. The mathematical model that describes diffusion of carbon and the precipitation of M23C6 and M7C3 has been studied. A criterion to judge when the transformation of M23C6 to M7C3 is over and M7C3 precipitates directly has been given in simulated calculation. By applying the model, the carburization of HK40 steel has been calculated by means of finite difference computation techniques. The pack carburization tests for the HK40 steel have been carried out at 1273 K. The comparison between the experimental and the calculated results show acceptable agreement.     

W18Cr4V高速钢离子渗氮层相结构与脆性研究

采用X射线衍射仪,金相显微镜及透射电镜分析W18Cr4V高速钢离子渗氮层相结构,采用连续加载压入法测定渗氮层脆性,分析了渗氮工艺对渗层相结构与脆性的影响。结果表明:离子渗氮工艺影响渗层相结构、含量及其分布,从而影响渗层脆性。     

铈对Fe-Cr-Ni-Nb-Ti-Al-W合金晶界MC相组成的影响

采用EDS研究了铈对铁基合金Fe Cr Ni Nb Ti Al W晶界析出相MC中M组成的影响。结果表明,随着合金中铈含量的增加,晶界MC相中铌量增加,而钛量相对下降。此结果证明,由于铌与碳的亲和力较钛大,当晶界附近的钛、铌等替代式溶质原子被铈原子驱逐并与碳结合时,有更多的铌参与了晶界MC相的组成。     

硅对烧结M3∶2高速钢回火相及力学性能的影响

为研究硅对烧结高速钢力学性能的影响,采用真空热处理炉在1230℃对含0.4%碳粉及硅添加量在0～3.0%的M3∶2高速钢进行烧结,在500～600℃对烧结后的试样进行二次回火.采用X射线衍射仪,扫描电镜及能谱分析等手段研究了不同硅添加量对回火态高速钢的物相特征及力学性能的影响规律.物相分析结果表明,添加硅后,硅主要分布在回火马氏体及M6C碳化物中,而在MC碳化物中含量较低.回火马氏体组织中硅的含量随硅添加量的增加而增加,同时,硅的添加还显著影响回火马氏体组织中铁素体相的晶格常数,在硅添加量为0.7%时,铁素体相达到最大的晶格常数.力学性能测试结果表明,适量硅的添加可提高二次硬化效果,添加0.7%硅的高速钢在550℃二次回火后获得了最佳的硬度和弯曲强度.