形状记忆合金在航空航天领域的应用与进展

叙述了形状记忆合金的功能特性,并介绍了NiTi形状记忆合金在航空航天领域的应用及其进展。     

Fe-Mn-Si-Cr-Ni合金在γ+α'复相状态下的形状记忆效应

用Ｘ射线衍射和ＴＥＭ方法研究了Ｆｅ－１４Ｍｎ－５Ｓｉ－９Ｃｒ－５Ｎｉ合金的应变诱发γ→ε和γ→α’马氏体相变行为,测试了几种合金为单相奥氏体以及奥氏体加α‘马氏体复相原始组织的形状记忆效应。探讨预应变前原始组织中存在的α’马氏体对形状记忆效应的作用。实验结果证实,这些合金从奥氏体加一定体积分数的α‘马氏体复相组织开始预应变,加热逆相变形状回复后,具有更高的形状回复率。     

有色合金的热弹性马氏体相变及其应用

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。     

磁性形状记忆合金的研究现状及发展

磁性形状记忆合金是一种新发展起来的形状记忆材料，合金具有大恢复应变、大输出应力、高响应频率和可精确控制的综合特性，有望成为压电陶瓷和磁致伸缩材料之后的新一代驱动与传感材料。系统阐述了近年来磁性形状记忆合金的研究进展，并着重介绍了目前研究最多的Ni-Mn-Ga合金的结构、相变、形状记忆效应、制备方法及其在应用方面的一些新的研究成果，并提出了磁性形状记忆合金需要深入研究的问题及其发展方向。     

冷热循环对Ni─Ti形状记忆合金马氏体相变及形状记忆效应的影响

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。     

Fe对Ni-Mn-Ga形状记忆合金相变和力学性能的影响

研究了Fe含量对Ni₅₆Mn_25-xFe_xGa₁₉(x=0~10)合金的微观组织结构、相变行为、力学性能和记忆特性的影响规律.当x ≤ 4时,Ni₅₆Mn_25-xFe_xGa₁₉合金仍然保持着单一的四方结构马氏体相;当x ≥ 6时,合金呈现为马氏体相和面心立方γ相组成的双相结构.相对于马氏体相,γ相为富Ni和富Fe相,其含量随Fe含量的增加而增加.随着Fe含量增加,合金的马氏体相变温度逐渐降低,其峰值温度从x=0时的356℃降低至x=10时的170℃,这主要归因于马氏体相尺寸因素和电子浓度的综合作用.通过添加Fe替代Mn在合金中引入的γ相可提高合金的强度和塑性,但最大形状记忆回复应变从x=0时的5.0%降低到x=6时的2.0%.     

形状记忆合金工业应用研究的进展

回顾的形状记忆合金的形状记忆效应和超弹性近年来在驱动器、智能材料和阻尼材料等方面的应用研究状况,并通过举例来展示形状记忆合金的美好未来。     

热处理工艺对CuZnAl形状记忆效应的影响

本文研究了不同的淬火时效工艺对Cu-26.16％Zn-3.79％Al(wt％)形状记忆合全马氏体相变的影响。试验结果表明:将合金加热到β单相区淬火后,立即在β_1状态时效一定时间(30～60min),可获得稳定的形状记忆效应,并保持马氏体热弹性特征。随着淬火温度的提高,M_3上升,热滞减少,记忆性能变佳;但淬火时效的温度过高,又会引起晶粒粗大,对疲劳强度有害。     

重熔镍钛合金的形状记忆效应分析

采用不同的工艺及设备对近等原子比的形状记忆合金进行重熔,获得铸态组织形状记忆合金,对采用不同坩埚所制备出的NiTi合金进行对比分析,采用金属坩埚所得到的形状记忆合金的成分满足医疗器械及外科植入物用NiTi形状记忆合金的成分要求,且具有良好的形状记忆效应。     

Aging Effects in Copper-Based Shape Memory Alloys

Aging of three copper-based shape memory alloys was studied by measuring the time dependence of hardness, martensitic transformation temperatures, lattice parameters, and shape memory capability at temperatures in the range 200 to 450°C. The ultimate loss of the shape memory effect in each alloy was preceded by changes in the other properties which resulted from thermally activated processes having activation energies in the range 60 to 80 kJ mol^-1. At temperatures above about 300°C the aging process involved the eventual formation of α and γ₂ phases. Although the activation energy appears to be insensitive to temperature and alloy composition, at lower temperatures other thermally activated processes, such as change in the type or degree of order, may, at least in the initial stages, be significant aging phenomena.     

Ni-Ti形状记忆合金中的相变

根据作者的工作、并结合新近文献,对近等原子Ni-Ti合金中的相变作了系统的综述,包括:相变的顺序,无公度相变,R相变,马氏体相变,合金成分及热循环对相变临界温度的影响,逆相变及沉淀。     

TiNiZr形状记忆合金的性能研究

系统地研究了锆对TiNiZr形状记忆合金性能的影响，对Ti49.4-xNi50.6Zrx(x=0,1,2,3)三元合金的相变温度进行了研究，表明合金相变温度随锆含量的增加先降后升；对合金系进行了机械性能及记忆性能研究，发现加锆后合金的机械性能和记忆性能都获得提高；此外还对Ti46.4Ni50.6Zr3的脆性根源进行了初步探讨。     

铁基形状记忆合金热塑性

研究了Fe-Mn-Si形状记忆合金热塑性。结果表明:合金中硅含量的增加可提高合金的记忆效应,却严重损害合金热塑性;微量元素Mg的加入可大大改善合金的热塑性,而不降低记忆效应。由于Mg元素的加入,含Si量达4%的Fe-Mn-Si形状记忆合金也能顺利地热轧成无缝管,提高了Fe-Mn-Si形状记忆合金实用性。     

The Application of Ni - Ti Shape Memory Alloys as Fasteners

Abstract

This article covers the various materials aspects of the shape memory alloys that go into the design of fastening devices. A brief overview of the shape memory phenomenon and the martensite transformation during free and constrained recovery has been given to clarify the role of the martensitic transformation in the success of this application. Finally, the design of an Ni-Ti-Fe fastening sleeve has been discussed.     

Ni-Mn-Ga磁控形状记忆合金中的马氏体相变

文章采用电弧熔炼法熔炼Ni48Mn31Ga21和Ni2MnGa两种合金,并对这两种合金进行了热处理,借助交流磁化率测定、金相显微镜观察、X射线以及磁化曲线等手段研究了Ni-Mn-Ga磁控形状记忆合金中的马氏体相变。结果表明：（1）Ni48Mn3lGa21合金在室温下发生了马氏体转变,而Ni2MnGa合金在室温下则未发生马氏体转变;（2）室温下Ni2MnGa合金的饱和磁化强度比Ni48Mn3lGa21合金高;对于Ni48Mn31Ga2l合金,其马氏体态的饱和磁化强度要高于奥氏体态。     

Microstructure and Shape Memory Characteristics of Powder-Metallurgical-Processed Ti-Ni-Cu Alloys

Even though Ti-Ni-Cu alloys have attracted a lot of attention because of their high performance in shape memory effect and decrease in thermal and stress hysteresis compared with Ti-Ni binary alloys, their poor workability restrains the practical applications of Ti-Ni-Cu shape memory alloys. Consolidation of Ti-Ni-Cu alloy powders is useful for the fabrication of bulk near-net-shape shape memory alloy. Ti₅₀Ni₃₀Cu₂₀ shape memory alloy powders were prepared by gas atomization, and the sieved powders with the specific size range of 25 to 150???m were chosen for this study. The evaluation of powder microstructures was based on a scanning electron microscope (SEM) examination of the surface and the polished and etched powder cross sections. The typical images showed cellular/dendrite morphology and high population of small shrinkage cavities at intercellular regions. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis showed that a B2-B19 one-step martensitic transformation occurred in the as-atomized powders. The martensitic transformation start temperature (M_s) of powders ranging between 25 and 50???m was 304.5?K (31.5?°C). The M_s increased with increasing powder size. However, the difference of M_s in the as-atomized powders ranging between 25 and 150???m was only 274?K (1?°C). A dense cylindrical specimen of 10?mm diameter and 15?mm length were fabricated by spark plasma sintering (SPS) at 1073?K (800?°C) and 10?MPa for 20?minutes. Then, this bulk specimen was heat treated for 60?minutes at 1123?K (850?°C) and quenched in ice water. The M_s of the SPS specimen was 310.5?K (37.5?°C) whereas the M_s of conventionally cast ingot is found to be as high as 352.7?K (79.7?°C). It is considered that the depression of the M_s in rapidly solidified powders is ascribed to the density of dislocations and the stored energy produced by rapid solidification.