Recovery Stress in a Ni-Ti-Nb Shape Memory Alloy with Wide Transformation Hysteresis

The effect of deformation on recovery stress of Ni144.7Ti46.3Nb9 alloy has been studjed using tensile test at various temperatures and TEM observation. It ls shown that the recovery stress increases with jncreasing total strain ET and reaches a maximum value (max) as ET= 9% but the maximum recov erV strain of the alloy is only about 4.6%. This is different from that of Ti-Ni binary alloy in which is obtained usually at maximum recovery strain and the reason of the difference is dis Cussed. Deformation temperature Td has a little effect on recovery stress when Td is less than Ms However, recovery stress decreases sharply when Td is higher than M, and lowers approximately down to zero near Msσ     

Ni-Ti-Nb宽滞后形状记忆合金管接头研究和进展

介绍了NiTiNb宽滞后记忆合金的发展以及形状记忆合金管接头工作原理.详细论述了NiTiNb宽滞后记忆合金管接头制备加工特点,结构设计思想以及扩径工艺.并介绍了一种气压管道连接用的小尺寸记忆合金管接头的研制.     

Transformation, Deformation and Microstructure Characteristics of Ru50Ta50 High Temperature Shape Memory Alloy

The basic martensitic transformation(MT)properties of Ru50Ta50 alloy, i.e. MT temperature(MTT), temperature hysteresis(△T), and MT heat(△H)were investigated in this paper. The effects of heat treatment and thermal cycling on MT behavior of Ru50Ta50 alloy, the deformation and microstructure characteristics of Ru50Ta50 alloy were also studied for its engineering application as high temperature actuator/sensor materials by means of differential scanning calorimetry, X-ray diffraction, transmission electron microscope, optical microscope, and hardness test. The results showed that a two-stage reversible MT takes place in Ru50Ta50 alloy.The two-stage MT starting temperatures(M1s, M2s)and the temperature hysteresis(△T1, △T2)are 1047,784 and 11, 14℃, respectively. No significant effect of aging treatment and thermal cycling on MTT and △T of Ru50Ta50 alloy were observed, but △H decreases slowly with increasing thermal cycles. The hardness and brittleness of Ru50Ta50 alloy are high. The deformation mode of RuTa alloys is twinning.     

Microstructure, Compression Property and Shape Memory Effect of Equiatomic TaRu High Temperature Shape Memory Alloy

The microstructure, phase transformation, compression property and strain recovery characteristics of equiatomic TaRu super high temperature shape memory alloy have been studied by optical microscope, XRD, DTA, compression tests and TEM observations. When cooling the alloy specimen from high temperature to the room temperature,β(parent phase)→β′(interphase) →β"(martensite) two-step phase transformations occur. The microstructure at room temperature show regularly arranged band morphology, with the monoclinic crystal structure. The twinning relationship between the martensite bands is determined to be (101) of Type I. Reorientation and coalescence of the martensite bands inside the variant happened during compression at room temperature. The β′→β reversible transformation contributes mainly the shape memory effect, with the maximum completely recovery strain of 2%.     

CuZnAlMnNi形状记忆合金马氏体相变焓的研究

采用差示扫描量热分析技术在５℃／ｍｉｎ以及在超低降温速率下，研究了ＣｕＺｎＡｌＭｎＮｉ形状记忆合金马氏体相变的热焓。通过实验和计算，由母相向马氏体转变时单位质量的相变总焓、热容改变焓和马氏体相变焓分别是３．２２Ｊ／ｇ、１．８８Ｊ／ｇ和１．３４Ｊ／ｇ。     

TiNi记忆合金的马氏体相变与形状记忆效应

对近些年来有关ＴｉＮｉ记忆合金中马氏相变和形状记忆效应的最新研究成果进行综合评述。主要内容包括马氏体的形成，相变晶体学和变体自协作以及变形行为和形状记忆效应。     

热处理对CuAlNiMnTi形状记忆合金相变滞后的影响

本文用电阻法、金相分析、电镜分析及X射线衍射等研究了热处理对CuAlNiMnTi形状记忆合金相变滞后(A_f-M_■)的影响。研究结果表明:淬火合金时效处理时,相变点急剧下降,时效初期相变滞后明显增大,后趋于稳定。淬火合金600℃中温处理时,相变点下降,相变量减小。而热弹性马氏体相变类型则从Ⅰ型转变到Ⅱ型,然后再转到Ⅰ型,伴随着热弹性马氏体相变类型的变化,相变滞后开始降低,然后增加。这是因为时效处理时析出NiAl基相,中温处理析出α相所致。     

热处理对NiTi形状记忆合金的相变的影响

对含Ti 50.8%的NiTi形状记忆合金在300℃、400℃、500℃保温不同时间进行时效处理,然后通过差示扫描量热仪DSC对其相变温度点进行测定,发现经时效处理调节后,Af最大可下降20~30℃左右,而Ms变化不大。通过不同时效温度和保温时间的DSC曲线比较,得出热处理对其相变温度点的影响规律,即在300~500℃时效处理时,保温时间越短,Af降低越明显,在相同保温时间时,保温温度越低,Af降低越明显。     

Heat Treatment of Ni-Ti Alloy for Improvement of Shape Memory Effect

Nickel-Titanium alloys with stoichiometric single phase and non-stoichiometric dual phase structures of NiTi and NiTi+Ni3Ti are produced through high speed induction melting and combustion synthesis of pure Ti/Ni elements. Both alloys are homogenized at 1273 K for two hours, rolled into thin strips of 0.3 mm thickness, solution treated at 1273 K for two hours under vacuum and finally quenched in water. Effect of ageing on austenite/martensite and intermediate phase transformation temperatures are investigated. Results show that transformation temperatures and reversible shape memory properties comparable with those required for bioengineering applications such as manufacturing of artificial hand prostheses can be obtained through careful control of the chemical composition and the heating processes.     

Effects of Predeformation on the Reverse Martensitic Transformation of TiNi Shape Memory Alloy

1. IntroductionIt is well known that near-equiatomic TiNt alloyscan show excellellt shape memory effect and pseudoelasticity in a strain range up to about 8%[1]. In manyengineering applications, TiNt alloy is usually predeformed in the martensitic state and then heated forproviding large recovery stress, strain or energy[2].Predeformation in the martensitic state causes themaltensite variallts to rearrange themselves to a preferelltial orientation under the effect of the appliedstress[3I. As…     

热处理温度对变形后TC17合金微观组织的影响

目的 研究热处理温度对变形后TC17合金微观组织演化和组织形态分布的影响。方法 对变形后网篮组织TC17合金开展热处理试验,定量分析α相球化率、体积分数随热处理温度的变化情况,采用两点相关函数表征不同热处理温度下TC17合金混合组织形态分布。结果 随着热处理温度的升高,变形后TC17合金α相球化率增大,体积分数减小。不同热处理温度下片层α相和等轴α相对应的两点相关函数曲线波动程度不同。结论 变形程度及热处理温度较低时,随着热处理温度的升高,等轴α相的分布均匀程度升高,片层α相的分布均匀程度降低。当变形程度及热处理温度较高时,随着热处理温度的升高,由于α相体积分数的迅速减小,等轴α相的分布均匀程度降低。     

退火温度对冷轧Ti-13V-3Al-0.5Cu形状记忆合金组织结构与马氏体相变的影响

使用XRD、TEM、DSC和室温拉伸等分析测试手段,对冷轧后经不同退火温度处理的Ti-13V-3Al-0.5Cu(%,原子分数)合金微观组织结构,马氏体相变行为,力学性能和形状记忆性能进行了研究。经冷轧、退火处理后,合金在室温下的组织主要为α"马氏体相,存在少量残余β母相、α相和Ti₂Cu第二相。随着退火温度的增加,合金形状记忆性能先升高后降低;当退火温度为750℃时,在预应变量为6%的前提下可实现5.3%的可回复应变。其组织结构观察结果表明,经冷轧、退火处理后,合金中α"马氏体形貌由“V”字型自协作组态向择优取向的单一取向马氏体板条转化,界面可动性提升,马氏体临界再取向应力降低,形状记忆性能提高。     

TiNi基高温形状记忆合金的马氏体相变与形状记忆效应

综述了Ti-Ni基高温形状记忆合金中的马氏体相变和形状记忆效应最近研究进展。Ti-Ni基高温形状记忆合金主要包括用Ti-Ni-Pd,Ti-Ni-Pt,Ti-Ni-Zr和Ti-Ni-Hf等。对Ti-Ni基高温形状记忆合金体材料、薄带和薄膜中的马氏体相变、组织结构、形状记忆效应以及超弹性性能等进行了评述和归纳。值得注意的是,通过适当的时效处理可调节相变温度,显著改善Ti-Ni-Hf高温形状记忆合金的开头记忆效应和超弹性性能,其主要原因在于时效的Ti-Ni-Hf合金中析出纳米级析出相导致基体强度升高。采取适当的制备和加工方法,提高合金的马氏体相变温度,改善合金的开头记忆效应,是当前TiNi基形状记忆合金研究的主要发展趋势。     

钛镍铪高温形状记忆合金的研究进展

介绍了钛镍铪高温形状记忆合金的研究进展,简述了钛镍铪合金的制备与加工方法,着重阐述了钛镍铪的相变特性、显微组织结构、单程及双程形状记忆效应、超弹性行为、机械特性和相应的微观机理,最后提出了需要进一步研究的问题。     

Cu－Zn－Al－Mn－Ni－Ti合金的显微组织及力学行为

本文利用电子拉伸试验、扫描电镜、金相显微镜研究了Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ－Ｎｉ－Ｔｉ合金的细化效果、断裂方式、记忆性能及伪弹性。结果表明：试验合金的铸态、轧态和淬火态组织得到明显细化。晶粒细化后合金室温拉伸断裂强度为７５０ＭＰａ，断裂应变为６．６％，同未细化的Ｃｕ基记忆合金相比强度大大提高，塑性也有所改善。低温拉伸时呈穿晶断裂，断口主要为准解理台阶；高温拉伸时呈微孔聚集型断裂。试验合金的室温完全可恢复应变为４．０％，完全伪弹性恢复应变为４．５％，均达到了多晶体材料的理论平均值。     

高温形状记忆合金研究进展

本文以ＴｉＮｉ基、ＮｉＡｌ基、Ｃｕ基以及ＴｉＰｄ基高温形状记忆合金为主，简要综述了高温形状记忆合金的研究现状及其发展前景。     

固溶温度对Cu-18Al-10Mn合金相变温度和形状记忆性能的影响

对不同固溶温度对Cu-18Al-10Nn形状记忆合金的记忆性能和马氏体转变温度的影响进行研究。结果表明,在650℃至900℃范围内,经淬火加沸水时效,合金的形状回复率随着固溶温度的升高而升高,在850℃左右达到最大值,并趋于平缓。随着固溶温度的升高,合金的马氏体转变温度提高。     

形状记忆合金元件的尺寸效应

对形状记忆合金元件的尺寸效尖进行了较深入的研究。除对其力的尺寸效应进行了研究外,还对其动作时间、响应时间、输出功率等随尺寸的变化情况进行了研究。研究后发现,形状记忆合金元件的形状回复力与特征尺寸的二次方成正比;其动作时间、响应时间与特征尺寸的一次方成正比;其输出功率与特征尺寸的二次方成正比;其功率／体积比与特征尺寸的负一次方成正比。因此,形状记忆合金是微机械领域能够采用的一种非常重要的功能材料。     

Factors Affecting Transformation Temperatures in Fe-Mn-Si-Cr-Ni Shape Memory Alloy

1. IntroductionFe-Mn-St-Cr-Ni shape memory alloys exhibit notonly a good shape memory effect (SME), but also agood corrosion resistanced'2] ) compared with Fe-MuSt alloys. Fulthermore, it can be used in manufacturing pipe couplings because of its high phase transformation temperatures and great thermal hysteresis.But the recovery strain in these alloys is still low (lessthan 2%), which licits their application in pipe couplings. Therefore, to increase the recovery strain iskey to their pra…