加热速度对Cu—Zn—Al—Mn淬火态合金马氏体逆相变的影响

用直流电阻法对Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ淬火态试样在不同加热速度下的马氏体逆相变进行了研究。结果表明，加热速度对Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ水淬及油淬试样的逆相变有较大的影响，尤其对水淬试样，加热速度慢到一定程度可以阻止马氏体逆相变的发生，或者使逆相变中出现反向过程，即ＤＯ３→Ｍ１８Ｒ转变。在慢速加热时，同时存在着马氏体时效及母相时效两种时效作用。加热速度越慢，这两种时效作用影响越大，从而使马氏体逆相变表现     

微量Zr对Cu－Zn－Al合金冷变形能力的影响

研究了微量Ｚｒ对Ｃｕ－Ｚｎ－Ａｌ合金再结晶规律和机械性能的影响．结果表明：在该合金中添加０．２４％Ｚｒ，再结晶温度升高，晶粒明显细化，但β相的含量也增多，使冷变形能力提高不明显．     

热循环对Cu－Zn－Al合金双程记忆效应的影响

本文研究了热循环对Ｃｕ－Ｚｎ－Ａｌ形状记忆合金双程记忆效应的影响。结果表明：双程记忆恢复率随着热循环次数的增加而不断衰减。     

Cu－Zn－Al形状记忆合金的成分设计

本文提出了Ｃｕ－Ｚｎ－Ａｌ形状记忆合金成分设计的一种简便方法，其计算结果与实验结果相符合。     

缺陷对Cu—Zn—Al形状记忆合金内耗的影响

本文通过不同淬火温度和不同激振时间对Cu-Zn-Al形状记忆合金耗影响的研究,探讨了晶体缺陷在合金内耗中的作用。结果表明:一定数量的缺陷将会引起内耗值的提高,Cu-Zn-Al合金作为阻尼材料在使用过程中由于缺陷增多阻尼性能虽有所降低,但长时间后仍有相当高的内耗值(Q~-1～5×10~-2),因此有较高的使用价值。     

脉冲电流对Zn－22Al合金超塑性力学行为的影响

本文以普通处理的Ｚｎ－２２Ａｌ合金板坯为对象，研究了脉冲电流对其超塑性力学行为的影响．实验结果表明：在脉冲电流作用下，合金的延伸率和应变速度敏感性指数有了很大提高，流动应力降低．在高应变速率（３．３×１０（－２）ｓ（－１））下，该合金仍具有很高的延伸率．最佳超塑变形温度向低温度方向偏移．合金的超塑变形可在更低温度下进行．     

Influence of stresses on martensitic transformation in ferromagnetic shape memory Ni_(50)Mn_(19)Fe_6Ga_(25) ribbons

~~Influence of stresses on martensitic transformation in ferromagnetic shape memory Ni_(50)Mn_(19)Fe_6Ga_(25) ribbons1. Ullakko, K., Huang, J. K., O'Handley, R. C. et al., Large magnetic-field-induced strains in Ni2MnGa single crystals, Appl. Phys. Lett., 1996, 69(13): 1966-1968. 2. James, R. D., Wuttig, M., Magnetostriciton of martensite, Philos. Mag., 1998, A 77: 1273-1275. 3. Wu, G. H., Yu, C. H., Meng, L. Q. et al., Giant magnetic-field-induced strains in H…     

Reverse Transformation Behavior of TiNi Shape Memory Alloys Prestrained in the Parent Phase

1 IntroductionShape memory alloys (SMAs) prestrained at a tem-perature belowAs(the reverse martensitic transformationstartingtemperature) can generate a large stress or me-chanical energy when constrainedly heated at aboveAf(the reverse martensitic transformation finishing tempera-ture) ,therefore they are regarded as one of the most im-portant actuatorsinsmart composites[1-4].The relationshipbetweenthe prestrain level and the reversible martensitictransformationof TiNi SMAs has beenstudie…     

Ni52.5Mn23.5Ga23.6Tb0.4磁性形状记忆合金马氏体相变和磁感生应变的研究

研究多晶合金Ni52.5Mn23.5Ga24的马氏体相变特征和磁感生应变性能,分析了稀土元素Tb对合金马氏体相变和磁性能的影响.研究结果表明,添加Tb使合金Ni52.5Mn23.5Ga24的马氏体相变温度提高到室温以上,并且降低了合金的温度滞后,在一定压力的作用下合金磁感生应变值增大.     

Influence of stresses on martensitic transformation in ferromagnetic shape memory Ni<Subscript>50</Subscript>Mn<Subscript>19</Subscript>Fe<Subscript>6</Subscript>Ga<Subscript>25</Subscript> ribbons

The influence of stresses on martensitic transformation in Ni₅₀Mn₁₉Fe₆Ga₂₅ melt-spun ribbons was studied. X-ray diffraction examination shows that the ribbon has a pure cubic L2₁ phase at room temperature and that the ribbon surface exhibits [100] preferentially oriented texture, while the [110] axis is about 45° tilted from the normal of the ribbon. By calculating the d spacing at different angles with the length direction of the ribbon, the tension was observed. It was found that the direction of the stress was along [010] direction of the oriented textured grains. During cooling, there is no obvious structural transition observed in as-spun ribbons. However, when the ribbons were annealed at 900 K for 24 h, the tension along [010] direction disappeared and the structural transition from cubic to tetragonal occurred obviously during cooling. It indicates that it is the tension along [010] direction to suppress the martensitic transformation in the as-spun ribbons.     

一种微合金化马氏体不锈钢的连续冷却转变研究

用膨胀法结合金相与硬度分析研究了一种新型水轮机叶片用V、N微合金化CrNiMo不锈钢的连续冷却转变行为,获得了该钢的连续冷却转变（CCT）曲线及不同冷却条件下的显微组织和硬度。结果表明,试验用钢的1、3、和温度分别为580℃、730℃、295℃和190℃,其贝氏体和铁素体分别在冷速小于0.5和0.2℃/s时出现,冷速在0.056~0.5℃/s之间时,硬度随着冷速的增大迅速增加,尔后随着冷速的增大,硬度缓慢升高。     

M(o)ssbauer and electron microscopy study of martensitic transformations in an Fe-Mn-Mo alloy

The kinetic,morphological,crystallographic,and magnetic characteristics of thermally induced martensites in Fe-13.4wt%Mn-5.2wt% Mo alloy were investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),and M(o)ssbauer spectroscopy.The experimental results reveal that two types of thermal-induced martensites,ε(hcp)and αˊ(bcc)martensites,are formed in the as-quenched condition,and these transformations have athermal characters.Mo addition to the Fe-Mn alloy does not change the coexistence of ε and αˊ martensites with the Mn content between 10wt% and 15wt%.Besides,M(o)ssbauer spectra reveal a paramagnetic character with a singlet for the γ(fcc)austenite and ε martensite phases and a ferromagnetic character with a broad sextet for the αˊ martensite phase.The volume fraction of αˊmartensite forming in the quenched alloy is much more than that of the ε martensite.     

Simulation of transformation mechanism of martensites in Ni_(62.5)Al_(37.5) alloy

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Actuation Mechanism of Two-step Reverse Transformation Behavior in TiNi Alloys Deformed at Parent Phase

1　IntroductionTiNishapememoryalloys (SMAs)arethepromisingfunctionalmaterialstobeusedasimportantactuatorsinmicromachinesandintelligentmachinesduetotheirlargeoutputstrainorstress[1,2 ] .ItiswellknownthattheSMAsdeformedatmartensiticphasehaveacapableofgeneratingforceormotionwithanenergyinputbyheating .Theac tuationcharacteristicoftheSMAsiscloselyrelatedtotheirdeformationformationandtemperature (thestateoftheSMAs) .Inotherwords ,theactuationcharacteristicoftheSMAsisdependentontheirreversema…     

升温速率对沥青燃烧和气态产物释放特性的影响

采用热重-傅里叶变换红外光谱联用实验分析不同升温速率下沥青燃烧的失重过程,得到沥青燃烧过程中气态产物的析出规律,并利用Kissinger法计算沥青燃烧的动力学参数,为揭示火灾中沥青的燃烧机理和指导阻燃抑烟沥青设计提供重要的理论依据. 结果表明,沥青燃烧过程主要包括有氧热解和重质组分燃烧2个阶段,且两阶段的反应机理不同. 沥青有氧热解阶段包含3个失重峰,分别对应饱和分、芳香分和胶质的热解,3种成分燃烧的活化能依次增大;随着升温速率的增大,3个失重峰出现重叠,最大失重速率明显增加,气态产物的红外光谱吸收峰强度逐渐增强. 重质组分燃烧阶段的活化能相比胶质有氧热解更低,最大失重速率及红外光谱吸收峰强度随升温速率变化不大.