共查询到14条相似文献,搜索用时 62 毫秒
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It is well known that the morphologies of the α martensite formed from the γ phase in ferrous alloys are classified into five types of lath, butterfly, (225)A type plate,lenticular and thin-plate. Among those α martensites, onlythe thinplate martensite, which is characterized by containing a high density of transformation twins, has a potential of exhibiting a perfect shape memory (SM) effect.Recently the present authors found in Fe-Ni-Si alloys that the thin-plate martensite is formed by the introduction of fine and coherent γ-(Ni,Fe)3Si particles with a L12 ordered structure in the austenite matrix due to ausaging. In the present study, the SM properties of the ausaged Fe-Ni-Si alloys with the thin-plate martensite are investigated by a conventional bending-test. The effects of the addition of Co to the Fe-Ni-Si alloys on the martensitic transformation and the SM properties are also investigated. It is shown that while the ausaged Fe-Ni-Si ternary alloys exhibit an imperfect SM effect due to reverse transformation from stress-induced thin-plate martensite to austenite, the SM properties are improved by the addition of Co. An almost perfect SM effect is confirmed in the Fe-Ni-Si-Co alloys by heating to 1 100 ℃ after deformation at -196 ℃. 相似文献
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徐祖耀 《有色金属材料与工程》1989,(6)
综述本文作者及其合作者对有色合金的热弹性马氏体相变及其在形状记忆中应用的已发表的工作。在热力学研究、M_s 及 A_s 计算的基础上,本文提出材料中发生热弹性马氏体相变的必需条件。扼要总结我们对 Ni-Ti 及 Cu-Zn-Al 合金中的相变及形状记忆效应的工作。 相似文献
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通过电阻及回复特性的测定,研究了在冷热循环条件下NiTi形状记忆合金记忆效应的稳定性问题。实验结果表明:对不同的NiTi合金固溶处理后,冷热循环对其形状记忆效应均产生影响。但时该合金在再结晶温度下时效处理或退火,冷热循环对其相变温度几乎均不产生影响。同时对产生以上规律的内在机制进行了初步探讨。 相似文献
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通过扭转法和电阻测量法对Cu-Zn合金的形状记忆效应进行了实验研究。发现在Ms点以上,不存在热弹性马氏体的情况下,由应力诱发马氏体可以引起形状记忆效应。另外,在Ms点以下有热弹性马氏体的情况下,根据实验结果可以证明,应力诱发马氏体在形状记忆效应中仍然起主要作用。 相似文献
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预变形和时效对NiTi合金相变的影响 总被引:3,自引:0,他引:3
对Ti-50.8at%Ni形状记忆合金丝施加不同的预变形,随后在不同的温度时效,研究了预变形、时效温度与NiTi形状记忆合金的相变特性之间的关系。结果表明,预变形和时效对NiTi形状记忆舍金的相变特性有着显著的影响,可促使NiTi合金发生R相变,使NiTi形状记忆合金在较窄的温度区间内发生B2-R-B19’三种相变,为进一步研究NiTi形状记忆合金的性能提供了方便。 相似文献
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形状记忆效应是基于马氏体相变及其逆转变,相变时母相与马氏体相之间存在严格的晶体学取向关系。根据唯象理论,相变织构是可以预估的。同样地对于相变应变也存在取向关系,通过多晶材料的织构分析也可以预估。铜基形状记忆合金沿<100>方向呈最大的相变延伸,通过适当的热机械处理可以获得沿同轧向成45°方向的最大强度的<100>织构取向分量,因而有最佳的记忆效应。 相似文献
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The influence of heating rate on double reversible transformation in CuZnA1MnNi shape memory alloy was investigated by differential scanning calorimetry. It was found that rapid heating inhibits X→M transformation but is fa vorable to the reverse martensite transformation, giving rise to the approach of the two transformation peaks. With the decrease of heating rate, the two transformation peaks separate gradually. 相似文献
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对成分(at)为Ti-51.28%Ni合金的相变过程用电阻、金相法进行了研究.发现该合金加热过程中发生M→R+M→B2转变,冷却时则有M→R+M→B2转变.并用电阻-温度曲线测定了不同热处理工艺条件下合金的相变温度,讨论了固溶时效处理制度对马氏体相变及R相变的影响,也讨论了提高合金形状记忆效应稳定性的各种方式,结果表明,“高温固溶,中温时效”是有利于该合金马氏体相变的最佳热处理工艺.也是提高其形状记忆效应的有效途径。 相似文献
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研究经不同条件热处理的Cu-8.9Al-12.4Mn-0.07B低温形状记忆合金的结构及相变行为,发现B的添加能细化晶粒,并抑制室温时效过程中Cu9Al4(γ2)相的析出。 相似文献