交流磁场对Fe-16Cr-2.5Mo合金阻尼性能的影响

采用改进的JN-1型倒扭摆内耗仪研究了外加交流磁场对Fe-16Cr-2.5Mo合金阻尼性能的影响.试验结果表明,在交流磁场作用下,合金的阻尼性能随磁场强度的增加先增大后减小,但衰减速度超过直流磁场.通过理论推导发现,导致这一变化的原因是交变磁场使畴壁处于振动状态,其振动幅度比直流磁场的大.     

Fe-13Cr-2.5Mo合金阻尼性能及磁畴的观察

利用拉伸试验机分析了Fe-13Cr-2.5Mo阻尼合金的拉伸性能,用倒扭摆仪测试了该合金的阻尼性能,利用Fe3O4磁流体在光学显微镜下观察到Fe-13Cr-2.5Mo阻尼合金的磁畴及在磁场下磁畴结构的变化。实验表明,合金在900℃×1h退火,拉伸性能最好,抗拉强度为467MPa,伸长率达23%;在1100℃×0.5h退火,合金的阻尼性能最高,对数衰减率达0.16,但在该温度下随保温时间的延长,阻尼性能急剧下降。经过对合金加磁前后磁畴结构的观察发现,磁畴结构中楔形畴的产生是导致阻尼性能下降的重要原因。     

Fe-12Cr-2Al-3Mo合金减振性能的研究

从具体工程应用出发,研究了Fe-12Cr-2Al-3Mo合金的阻尼性能.采用倒扭摆测试仪测试合金丝材的内耗值,用振动测试仪测试合金圆桶构件的减振性能.结果表明,Fe-12Cr-2Al-3Mo合金内耗值明显高于0Cr18Ni9Ti不锈钢;圆桶构件的振动加速度峰值为0Cr18Ni9Ti不锈钢的1/5.利用磁畴结构可以解释Fe-12Cr-2Al-3Mo合金具有高减振性能的原因.     

退火态Fe-16Cr-2.5Mo阻尼合金磁致伸缩特性与阻尼性能的关系分析

采用改进的迈克尔逊干涉仪研究了Fe-16Cr-2.5Mo阻尼合金在800、900、1000、1100℃退火空冷下的磁致伸缩特性.用悬臂梁测试系统分析了退火态合金的阻尼性能.研究发现,随着退火温度的升高,Fe-16Cr-2.5Mo合金的饱和磁致伸缩系数λs和损耗因子η都在900℃出现峰值,分别达43.2×10-6和0.0622.合金的饱和磁致伸缩系数λs随温度的变化规律与损耗因子η一致.饱和磁致伸缩系数反映了磁机械效应的强弱程度,随着饱和磁致伸缩系数λs的增加,损耗因子η也逐渐增加,二者呈近似的线性关系.     

退火温度对Fe-7Al-0.5Ti合金阻尼性能和磁畴结构的影响

利用倒扭摆仪研究了不同退火温度对Fe-7Al-0．5Ti合金阻尼性能的影响，并借助水基磁流体分析了磁畴结构变化，利用扫描电镜分析了晶界析出物的形态及组成。结果表明，1000℃退火保温2h时，Fe-7Al-0．5Ti合金阻尼性能出现峰值。热处理温度越高，组织内应力和缺陷的减少使得磁畴的排列越来越整齐，磁畴宽度也越大，但晶界附近少量含Ti碳化物析出，导致局部成分和结构的非均匀化，不仅使得该区域磁畴细化，而且阻碍了畴界的移动．从而影响了阻尼性能的提高。     

Nb,Ti和Cu对Fe-13Cr-2.5Mo合金阻尼与腐蚀性能的影响

采用动态机械分析仪(DMA)和场发射扫描电镜(FESEM)研究了1.0%Nb,1.0%Ti和0.5%Cu(质量分数)添加对Fe-13Cr-2.5Mo合金阻尼性能和腐蚀性能的影响.结果表明:添加Nb的合金中,形成的大量(Nb,Mo)C相会阻碍磁畴壁的运动,严重影响合金的阻尼性能;当应变振幅大于3.5×10-5时,析出相(Nb,Mo)C与位错的交互作用会引起静滞后型位错阻尼Qdis-1,致使在高应变振幅区合金阻尼性能明显提高;加入Ti或Cu后合金晶界碳化物明显减少,而晶内析出相明显增多,导致合金的阻尼性能在低应变振幅区略有降低.点蚀结果表明,三种合金元素的添加都能提高合金的耐蚀性能,其中添加1.0%Ti的合金可同时获得良好阻尼性能和耐蚀性能.     

《110》取向Tb0.36Dy0.64(Fe0.85Co0.15)2合金的磁机械阻尼特性

采用区熔定向凝固方法,以480 mm/h速度制备了<110>取向Tb0.36Dy0.64(Fe0.85Co0.15)2合金棒.通过测试在0-0.325 T磁场范围内合金棒的应力-应变回线,计算了应力幅σm分别为-10,一30和一50 MPa的阻尼系数ΔW/W.结果表明,零磁场下的ΔW/W最大;随磁场强度增大,同一σm条件下的ΔW/W逐渐降低.在低磁场中,ΔW/W随σm的增加而降低;在高磁场中,ΔW/W随σm的增加而升高.利用不同预压应力下的磁致伸缩-磁化强度关系曲线,分析了磁场-应力复合加载条件下非180°磁畴和畴壁的运动形式.依据局部内应力理论,解释了合金棒的磁机械阻尼系数随外磁场强度和应力幅值变化的规律.     

退火及置换元素对Fe-Cr-Al基合金阻尼性能及强度的影响

制备了Fe-13Cr-6Al（原子分数,%）及用2%的Mo、Mn和Nb分别置换Fe-13Cr-6Al中的Cr,用0.5%和1%的Cu分别置换Fe-13Cr-6Al中的Al共6种合金.测试了各合金的阻尼性能和强度,通过金相观察和内应力分析研究了退火温度、冷却方式及合金元素对这两种性能的影响.结果表明：随着退火温度的升高,Fe-Cr-Al基阻尼合金阻尼性能升高,强度降低;随炉缓冷合金的阻尼性能高于水淬合金的阻尼性能,而前者的强度低于后者;0.5%Cu置换Al降低了位错与溶质原子之间的交互作用,但是提高了合金原子与基体原子的弹性交互作用,使合金的阻尼性能和强度都得到了提高.     

磁场热处理对FeCrCo合金组织性能的影响

研究了Fe-25Cr-12Co合金在不同拉速下对定向凝固组织以及磁场施加对合金热处理组织及磁性能的影响。用金相显微镜和TEM对合金的显微组织和结构进行分析,用型振动样品磁强计对合金进行磁性能测试。结果表明,提高拉速有利于减少合金中σ析出相但不利于合金的取向生长。磁场热处理有利于促进α1粒子由颗粒转变为长形状,并且改变合金磁性能,合金在平行于磁场方向的磁性能好于无磁场条件,而合金垂直于磁场方向的磁性能低于无磁场条件。     

V对Fe-Mn-Si合金不同变形条件下马氏体相变的影响北大核心CSCD

采用X射线衍射和透射电镜研究了V对Fe-Mn-Si合金不同变形条件下的马氏体相变特性的影响。研究表明:相同变形条件下,Fe-17Mn-5Si-2Cr-2Ni-1V合金中ε马氏体含量比Fe-17Mn-5Si-10Cr-5Ni合金的要多,且ε马氏体量的变化速率远低于Fe-17Mn-5Si-10Cr-5Ni合金。Fe-17Mn-5Si-10Cr-5Ni和Fe-17Mn-5Si-2Cr-2Ni-1V合金的应力松弛率均随停载时间的增加而增大,且Fe-17Mn-5Si-2Cr-2Ni-1V合金的松弛率大大低于Fe-17Mn-5Si-10Cr-5Ni合金。     

Magnetic anisotropy in Fe-25Cr-12Co-1Si alloy induced by external magnetic field

Structural and magnetic properties of Fe-25Cr-12Co-1Si alloy thermo-magnetically treated under different external magnetic field conditions were investigated. Orientation and morphology of the ferromagnetic α1 phase embedded in α2 phase matrix before and after step ageing are characterized by transmission electron microscope（TEM）. The results show that the ellipsoidal particles of ferromagnetic al phase are aligned along the direction of external magnetic field during isothermal magnetic ageing. Approximately 28% of the total coercivity can be attributed to the shape anisotropy of al phase particles induced by external magnetic field for Fe-25Cr-12Co-1Si alloy thermo-magnetically treated with a parallel magnetic field.     

Study on Thermomagnetic Treatment Fe-25.5Cr-12Co Permanent Magnetic Alloy

The magnetic properties and microstructure in a low cobalt Fe-25.5Cr-12Co alloy by different process of thermomagnetic treatment were investigated. It is found that magnetic properties are sensitive to parameters of thermomagnetic treatment process in magnetic field, including temperature, time and applied magnetic field. There are optimized isothermal aging temperature and time in different magnetic heat treatment conditions. High magnetic field strength could improve magnetic properties. Applied magnetic field has a great effect on microstructure of the Fe-25.5Cr-12Co alloy. The finer ferromagnetic α１ particles with suitable c/a ratio by high magnetic field magnetic heat treatment are attributed to improvement the magnetic properties.     

A study of impact toughness of Fe-Cr-X damping alloys

A study was carried out on the impact toughness of Fe- Cr- Х damping alloys. Two measures proved to be effective in improving impact toughness. One was to lower carbon plus nitrogen content to an ultra- low level. This method is suitable for single- phase ferrite alloy. The other is to use dual- phase damping alloys. The presence of martensite in Fe- Cr- Х alloys can enhance impact toughness remarkably, but lower damping capacity drastically. This shows the importance of achieving balance between mechanical prop-erties and damping capacity by properly controlling martensite volume fraction in dual- phase alloys.     

INFLUENCES OF ADDITIONS OF Nb, Ti AND Cu ON DAMPING CAPACITY AND CORROSION RESISTANCE OF Fe--13Cr--2.5Mo ALLOY

采用动态机械分析仪 (DMA) 和场发射扫描电镜 (FESEM) 研究了1.0\%Nb, 1.0%Ti和0.5%Cu (质量分数) 添加对Fe--13Cr--2.5Mo合金阻尼性能和腐蚀性能的影响. 结果表明: 添加Nb的合金中, 形成的大量(Nb, Mo)C相会阻碍磁畴壁的运动, 严重影响合金的阻尼性能;  当应变振幅大于3.5×10^-5时, 析出相 (Nb, Mo)C与位错的交互作用会引起静滞后型位错阻尼Q_dis^-1, 致使在高应变振幅区合金阻尼性能明显提高; 加入Ti或Cu后合金晶界碳化物明显减少, 而晶内析出相明显增多, 导致合金的阻尼性能在低应变振幅区略有降低. 点蚀结果表明, 三种合金元素的添加都能提高合金的耐蚀性能, 其中添加1.0%Ti的合金可同时获得良好阻尼性能和耐蚀性能.     

The structure and adhesion of oxide scales on Fe?Ni?Mo and Fe?Cr?Mo alloys

The Structure and Adhesion of Oxide Scales on Fe? Ni? Mo and Fe? Cr? Mo Alloys A preliminary study has been made of the structure and adhesion of oxide scales formed on Fe-1.8 wt.% Ni-0.3wt.% Mo and Fe-1wt.% Cr-0.5wt.% Mo in oxygen at 930°–1250°C. From 930°–1250°C, the Fe? Ni? Mo alloy oxidised at a slower rate that the Fe? Cr? Mo alloy, and both alloys oxidised at a slower rate than high-purity iron. Hot bend tests and hot tensile tests of a scale-metal joint revealed that the scales comprised a strongly adherent inner layer (enriched in Cr? Mo or Ni) and a weakly coherent bulk structure. In the Fe? Ni? Mo alloy, failure in the bulk scale occured along a smooth plane at the edge of the Ni-enrichment zone whereas in contras, for the Fe? Cr? Mo alloy, failure occured withing the Cr? Mo enriched zone adjacent to the scale-metal interface.     

基于马氏体区域化形成的免训练铸造Fe-Mn-Si-Cr-Ni形状记忆合金 Ⅱ.退火对形状记忆效应的影响

采用OM和铁素体测量仪研究了铸态Fe-18Mn-5.5Si-9.5Cr-4Ni合金的微观组织随退火温度的改变及其对合金形状记忆效应的影响.结果表明,在773-1173 K之间退火处理能进一步提高合金的形状记忆效应.经973 K退火30 min后,合金的可恢复变形量达到了6.4%,比训练4次的常规Fe-14Mn-5Si-8Cr-4Ni合金高1.2%.当铸态合金在低于1173 K退火30min后,δ铁素体仍为条状,变形时能使应力诱发ε马氏体以区域化的方式形成,合金具有良好的形状记忆效应;当退火温度高于1273 K时,δ铁素体将固溶到奥氏体中,体积分数减少.当退火温度进一步升高到1423 K时,δ铁素体的体积分数显著增加,形态由条状演变为岛状.条状δ铁素体体积分数的减少和岛状δ铁素体的形成导致δ铁素体不能有效分割奥氏体晶粒,合金的形状记忆效应显著下降.     

Oxidation behavior of Mn and Mo alloyed Fe-16Ni-(5-8)Cr-3.2Si-1.0Al

Oxidation tests were conducted on a master alloy, Fe-16Ni-(5–8)Cr-3Si-lA1, to which (0–4) wt/o pct Mn and/or Mo were added. Tests were conducted at temperatures ranging from 1073–1273 K for times up to 1000 hr. Additions of Mn resulted in formation of a dual oxide structure and decreased oxidation protection. Addition of Mo significantly improved oxidation protection by formation of an intermetallic Fe(Mo)Si precipitate that eventually formed a protective SiO₂ oxide sublayer. Increasing the Cr concentration in an alloy containing both Mn and Mo resulted in a slight increase in weight gain. To first order, the apparent oxidation activation energy for all the alloys was nearly constant, 121 kJ/mol, suggesting that the same mechanism controlled the oxidation for all compositions. The oxidation protection was related to the alloy components and concentration.     

Conductivity and Oxidation Behavior of Fe-16Cr Alloy as Solid Oxide Fuel Cell Interconnect Under Long-Stability and Thermal Cycles

Conductivity and oxidation behavior of Fe-16Cr alloy were investigated under long-term stability operation at 750℃ and thermal cycles from room temperature to 750℃.The results showed that the area specific resistance (ASR) of Fe-16Cr alloy increased over time and reached about 56.29 mΩcm ~(2 )after 40,000 h of long-term stability operation at 750℃ by theoretical calculation.The ASR of Fe-16Cr remained about 11 mΩcm ~(2 )after 52 thermal cycles from room temperature to750℃.The analysis of structure showed that the oxidized phase on the surface of Fe-16Cr was mainly composed of Cr _(2 )O _3and Fe Cr _(2 )O _(4 )spinel phase under long-term stability operation at 750℃.While the Cr _(2 )O _(3 )phase was mainly observed on the surface of Fe-16Cr alloy after 52 thermal cycles,the oxidation rates of Fe-16Cr alloy were 0.0142μm h~(-1 )and 0.06μm cycle~(-1 )under long-term stability operation and under thermal cycle,respectively.The property of Fe-16Cr alloy with 2.6 mm thickness met the lifespan requirement of interconnect for solid oxide fuel cell (SOFC) stacks.The Cr element all diff used onto oxidation surface,indicating that it was necessary to spray a coating on the surface to avoid poisoning cell cathode of SOFCs.Two 2-cell stacks were assembled and tested to verify the properties of Fe-16Cr alloy as SOFC interconnect under long-term stability operation and thermal cycle condition.