Research of Pipe Made of Cu -Zn -Si Shape Memory Alloy to Internally Sprayed Pipe Connection in Connected Technology

The copper-based shape memory alloy pipe joint was applied in the field of oil pipelines jointing as well as installing. It has many advantages than anything. In the paper, the basic principle and connection influence factors of copper-based shape memory alloy pipe joint were described. Experimental results shows the copper-based shape memory alloy pipe joints can be used in oilfield oil pipeline connection and it can solve the inner pipe joint corrosion damage problem by welding.

Effect of texture on internal friction of Cu-Al-Mn based shape memory alloys

Shape memory alloys (SMAs) are well-known as high damping materials. Recently,we have reported that the Cu-Al-Mn SMAs show a high internal friction as well as the other SMAs such as Ni-Ti, Cu-Zn-Al SMAs. Since the Cu-Al-Mn-based SMAs possess an excellent cold-workability, a strong recrystallization texture can be formed by thermomechanical treatment. The present authors demonstrated that the texture control is considerably effective for improving the SM properties and especially, in the Cu-Al-Mn-Ni SMAs with a strong {112}<110> recrystallization texture, a large pseudoelastic (PE) of about 7% can be obtained. Such a texture control is expected to enhance the damping capacity in the Cu-Al-Mn-based SMAs as well as PE. In this study, the effect of texture on the internal friction in Cu-Al-Mn and Cu-Al-Mn-Ni SMAs was investigated by tensile testing mode of Dynamic Mechanical Spectrometer (DMS). In sheet specimens with the {112}<110> texture, value of dynamic damping tanφ depends on the loading direction and an excellent damping capacity of tanφ= 0.1 can be obtained at the rolling direction in the martensite phase condition. Moreover, these Cu-Al-Mn-based SMAs show a high tensile strength over 600 MPa in the martensite phase. The present Cu-Al-Mn-based SMAs should have a great potential as the damping materials.

Structure design of high-performance Cu-based shape memory alloys

The effects of various structure factors on the properties(superelasticity mainly) of Cu-based shape memory alloys(SMAs) were systematically evaluated in this review article through literatures combining with our work. It is concluded that besides the decisive role of grain orientation, the grain boundary(GB) characteristics also play important roles in the superelasticity, which include GB area, GB type, GB morphology and GB direction in descending order of the effect significance. According to the above results, the prior principles of structure design are proposed for high-performance Cu-based SMAs from most to least important:(1) obtaining grain orientation with high phase transformation strain;(2) increasing grain size or reducing GB area;(3) obtaining straight low-energy GBs, especially low-angle GBs;(4) trying to make GB direction parallel to external stress. Consistent with the main or all principles, the bamboo-like-grained and columnar-grained(CG) Cu-based SMAs show excellent comprehensive properties.

THE FAILURE MECHANISM OF REVERSE SHAPE MEMORYEFFECT IN A Cu-BASE ALLOY

The interior structural evolution accompanying reverse shape memory effect (RSMEin a Cu-Zn-Al alloy was studied by means of transmission electron microscopy. It was found that RSME is closely related to bainitic transformation in this alloy during the isothermal reaction at moderate temperatures. At a given temperature and a certain external constraint stress, the shape memory effect depends mainly on the aging time.During the early stage, the shape memory effect enhances with the increase of reactiotn time. Then it will decrease gradually apon further aging. If the alloy is overaged, the stacking faults of bainite will disappear gradually by the motion of partial dislocations through which long range diffusion of solute atoms takes place, giving rise to the deterioration of RSME. When all the bainite transforms to α phase, RSME will lose completely.

MARTENSITIC TRANSFORMATION AND THERMAL STABILITY IN Cu-Al-Co AND Cu-Al-Zr ALLOYS

Cu-Al-Co and Cu-Al-Zr alloys were explored with Co or Zr additions in Cu-Al alloys for high temperature shape memory alloys. Samples were quenched after homogenized at 850℃ for 48h. It was found that both Cu-Al-Co and Cu-Al-Zr show AlCus martensitic phase at room temperature and exhibit martensitic transformation temperatures higher than 200℃, showing the potentials for developing as high temperature shape memory alloys. Thermal cycles were performed by DSC instrument on both Cu-Al-Co and Cu-Al-Zr alloys. The results show that Cu-Al-Co loses its martensitic transformation after five thermal cycles, and Cu-Al-Zr exhibits no martensitic transformation in the second thermal cycle.

THE TYPE II DEFECT IN 18R MARTENSITE IN A Cu-Zn-Al ALLOY

Type H defect in 18R martensite in a Cu-Zn-Al alloy has been studied by high resolution electron microscopy. It was found that Type H defect is not fault internal to martensite plate; rather,it is a stack of plates A and C. The rare observation of Type H defect is considered to be due to the fact that thc slice is too thin to exist for self-accommodation.

Texture Development of a Cold-rolled CuZnAl Alloy

In this paper, the textures of a CuZnAl alloy, produced d by cold rolling in the dual phase state, were studied. The alloy was heat-treated to obtain a microstructure of dual phases, then, cold-rolled with intermediate annealings. The pole figures of a and 3 phases were measured separately by the texture goniometer at the surface and center of rolled sheets. The orientation distribution function analysis showed that the a phase possessed a weak texture, and the 3 phase possessed a strong a-fiber texture. Compared the textures between the center and surface it was indicated that the textures were as a whole homogeneous. The formation of such two phase textures depended mainly on the volume percents of both phases as well as the recrystallization annealing.

Cu-Al-Mn-Zn-Zr记忆合金的应力诱发马氏体相变及其逆转变

利用拉伸实验、电阻-温度曲线测量、X射线衍射、金相与透射电镜观察等方法研究了Cu-18.4Al-8.7Mn-3.4Zn-0.1Zr(原子分数,％)合金应力诱发马氏体的稳定性与可逆性.结果表明:在Ms以上变形,实验合金发生应力诱发β1→M18R转变,但应力诱发马氏体转变很难进行完全,当变形量高达7.5％时,仍存在未发生应力诱发转变的母相.应力诱发马氏体的稳定性和可逆性与变形量大小有关,合金经大变形量变形后,即使在250℃油浴中回复,仍存在未发生逆变的应力诱发马氏体.在一定的变形条件下,经适量变形的应力诱发马氏体具有很高的可逆性和稳定性,实验合金在Ms以上10—50℃温度范围内变形6.5％-9.0％时,相变滞后宽度可达90℃以上,记忆应变>3.5％.

β1相非等温时效对Cu－Al－Ni－Mn－Ti合金热弹性马氏体转变的影响

研究了Ｃｕ－Ａｌ－Ｎｉ－Ｍｎ－Ｔｉ合金β１相非等温时效过程。在时效前期主要是ＤＯ３有序畴长大和畴内次近邻原子的高度有序化，它引起马氏体点升高。在时效后期，合金中发生了贝氏体转变，它使基体溶质原子富集，导致马氏体点下降，马氏体量减少。在更高的温度下，合金分解成平衡组织。

矿用管接头Cu-Al-Mn记忆合金材料的研究

介绍了两种Cu -Al-Mn形状记忆合金 ,测量其马氏体转变温度 ,发现 9R马氏体结构的合金相变滞后宽度远大于 18R 马氏体结构的合金。用于管接头 ,由于形状记忆效应 ,起到紧固连接作用 ,是具有工业应用前景的新材料。

Cu－Zn－Al－Mn－Ni－Ti合金第二相形成过程研究

加入微量Ｔｉ改变了Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ－Ｎｉ合金的凝固过程，凝固初期从液相优先结晶出树枝状Ｘ相，一次枝晶生长方向为〈１１１〉，在高温β相区固溶时Ｘ相球化形成稳定的Ｘ１相，同时析出Ｘｓ相Ｘｓ相以形核长大的方式从固相脱溶形成，其形貌、尺寸与处理温度、时间以及随后的冷却速度有关．随着温度升高，时间的延长，Ｘｓ相析出形态变化顺序如下：球形－立方形－梅花状－橄榄状．

淬火保温时间对Cu-Zn-Al合金形状记忆效应的影响

研究了淬火保温时间对Cu Zn Al合金单向形状记忆效应 ηO 和双向形状记忆效应 ηT 的影响。研究结果表明 ,随训练次数的增加 ,位错增加 ,晶格原子有序度降低 ,单向形状记忆效应先急剧下降 ,然后缓慢下降 ,趋于稳定。但是 ,随训练次数的增加 ,双向形状记忆效应都先急剧上升 ,然后缓慢上升 ,趋于稳定。淬火保温时间过短或过长 ,都使形状记忆效应降低。淬火保温时间必须适当 ,即要使溶质原子充分均匀化 ,保证母相充分有序 ,又不使晶粒过大 ,才有较好的单向形状记忆效应 ηO 和双向形状记忆效应 ηT。最佳和最差保温效果时的单向形状记忆效应 ηO 和双向形状记忆效应 ηT 可分别相差达 70 %左右。

高温宽相变滞后Cu-Al-Mn形状记忆合金的研究

通过恰当的成分设计 ,可得到具有较高马氏体相变温度及较宽相变滞后的Cu Al Mn形状记忆合金。用DSC(differentialscanningcalorimetry)及差热分析法测得 :Cu 13.5Al 2 .5Mn 1.36Zn合金的M 点(降温时马氏体相变最激烈的温度 )为 2 5 0℃ ;淬火后相变滞后宽度达到 16 7℃。此合金具有良好的单向形状记忆效应 ,在表面应变为 4 %时 ,淬火态弯曲变形试样的形状回复率达 95 % ,马氏体态长期时效对其影响不大 ,淬火后室温下 (马氏体态 )时效 2年 ,弯曲变形试样的形状回复率达 90 %。室温淬火后 ,合金的力学性能指标如下 :抗拉强度约 2 5 0MPa ,伸长率约 7% ,硬度为 190HB。这种合金具有性能稳定、可用温度及时间范围较宽、力学性能较好等特点。

Cu-Al-X形状记忆合金发展及研究现状

对Cu-Al-X合金的形状记忆效应、滞后效应和阻尼性能等进行了概括,并就目前限制Cu-Al-X SMAs得到应用的主要问题及相关解决方案进行了阐述。根据第三组元的不同,将现有合金系分类,并对其性能和发展分别做了介绍和展望。

热处理对Cu-Zn-Al形状记忆合金单程形状记忆效应的影响

研究了在SME法训练条件下 ,等温淬火热处理对Cu Zn Al形状记忆合金单程形状记忆效应 ηO 的影响及与“淬火 +上淬”热处理的比较。研究结果表明 ,等温时间如能保证合金充分有序化 ,又不使合金发生偏聚和析出其它相时 ,可获较好单程形状记忆效应训练效果。等温时间 8min的单程回复率 ηO 较佳 ,训练达到稳定时 ,比等温3min得到的最差的 ηO 值高出约 83%。随训练次数增加 ,位错增加 ,晶格原子有序度降低 ,单程形状记忆效应先急剧下降 ,后缓慢下降 ,最后趋于稳定。比较试验发现 ,“淬火 +上淬”处理比等温淬火处理具有更好的单程形状记忆效应训练效果。因为后者的母相 马氏体共格关系不如前者 ,并可通过时效获得最佳有序畴尺寸。经充分训练后 ,前者最终的单程回复率 ηO 比后者的高出 34%。

Cu-Al-Ni-Mn-Ti合金热弹性马氏体相变弛豫时间的研究

文章研究了Cu-12Al-5Ni-1.6Mn-1Ti形状记忆合金马氏体逆相变时弛豫时间与升温速率的关系。实验结果表明,马氏体逆转变时,弛豫时间随升温速率的增大开始迅速衰减,当升温速率较大时,逐渐趋于一个稳定值。马氏体逆转变量越少,弛豫时间越短,分布参数越大,并逐渐趋近于Debye滞弹性弛豫。

Cu基形状记忆合金的阻尼及记忆效应的应用

综合回顾了Cu基形状记忆合金的研究发展现状,并概述了其阻尼机制及分类,分析了Cu-Al、Cu-Zn系合金的阻尼能力和影响因素,并介绍了Cu基形状记忆合金的应用,提出了其应用推广前要解决的问题.最后给出了一些应用实例.

CuAlMnZnZr合金拉伸变形及其宽滞后效应

利用拉伸试验、电阻—温度曲线测量、光镜、Ｘ射线衍射及透射电镜分析方法研究了Ｃｕ－Ａｌ１０．２－Ｍｎ４．９－Ｚｎ４．６－Ｚｒ０．３合金的宽滞后效应。结果表明，随着应变的增大，该合金相变滞后增宽，马氏体可逆转变量减少。在应力下合金组织变化如β→２Ｈ转变、１８Ｒ→２Ｈ转变、某些变体择尤长大，变体间的合并是主要变形机制。这些运动导致了交叉组织、带状组织、锯齿状边界、孪晶碎片及位错缠结的产生，破坏了变体间界面共格关系，使得其在热激活作用下难以运动。这可能是产生宽滞后效应和使可逆马氏体量减少的主要原因。

Cu－Zn－Al合金中马氏体的有序化

利用Ｘ－射线衍射方法研究了４种不同淬火速度的Ｃｕ－１８Ｚｎ－１４Ａｌ合金马氏体结构及其有序化状态。随淬火速度的减慢．该合金次近邻（ｎｎｎ）有序度增强．而近邻（ｎｎ）有序度基本不变，其（１２Ｌ）与（２０Ｌ），（０４Ｌ）与（３２Ｌ或３２Ｌ）衍射峰对的分裂参数ρ＝｜ｓｉｎ２θ１－ｓｉｎ２θ２｜及单斜角β也变化甚微。此外，还根据该台金的晶体结构模型对其有序化状态进行了分析计算，认为ｎｎｎ有序增强时仅是Ｚｎ、Ａｌ原子沿ｂ轴发生交换．其对晶体对称性和晶格常数影响甚数．

热处理方法对Cu-Al-Mn合金形状记忆效应的影响

利用自制合金低温形变量测量装置以及测量低温电阻、低温膨胀、X-射线、扫描电镜等检测手段,研究热处理对55％Cu-35％Al-10％(Mn+Si)合金低温形状记忆性能的影响。合金试样较理想的热处理工艺为950℃保温10min+室温水淬+200℃回火10min,形状记忆温度为100K左右。自制的形变量测量装置可用于低温形状记忆性能测定试验。