NiTi形状记忆合金高温形变机制

Ni Ti形状记忆合金因具有独特的形状记忆效应和优异的机械性能,而在消防领域具有重要的应用。针对Ni Ti合金在消防领域中常会处于高温环境这一情况,利用差示扫描量热仪(DSC)、X射线衍射(XRD)和高分辨率透射电子显微镜(HRTEM)多种表征手段,分析Ni Ti合金的相变行为和微观结构,研究Ni Ti形状记忆合金的高温力学性能。     

激光选区熔化制备镍钛合金的研究进展

镍钛形状记忆合金因其具有良好的力学性能、生物相容性和耐蚀性,被广泛应用于各个领域,尤其是生物医学领域.同时,诸如心血管支架、骨植入物等应用对于成形件的结构及精度都提出了极大的要求.因此,对以SLM为代表的金属3D打印工艺在制备NiTi合金,以及其工艺参数对成形件质量、显微结构、相变温度和力学性能的影响进行了阐述.同时,列举了一些3D打印制备的NiTi合金在生物医学领域的应用实例,并指出了SLM制备NiTi合金存在的问题,最后对其今后的发展趋势进行了展望.     

NiTi基形状记忆合金相变温度的影响因素

NiTi基形状记忆合金的相变温度直接影响并限制了其应用领域,为了能够在更广阔的领域中应用NiTi基合金,需要有效而准确的控制NiTi基合金的相变温度.研究表明,NiTi基合金中Ni元素的含量以及合金中所包含的夹杂相,如NiTi2、Ni3 Ti2、Ni4 Ti3等均会影响合金的相变温度.同时,向NiTi二元合金中添加第三...     

NiTi形状记忆合金抗磨损性能的研究

为了弄清NiTi形状记忆合金的相与磨损性能之间的关系以及合金的磨损特征,研究了六种NiTi合金在相同条件下Ms转变温度对磨损量的影响.研究结果表明,Ni原子分数越高,合金硬度越高,β相含量越高,NiTi合金的抗磨损性能越好.     

NiTi形状记忆合金抗磨损性能的研究

为了弄清NiTi形状记忆合金的相与磨损性能之间的关系以及合金的磨损特征，研究了六种NiTi合金在相同条件下Ms转变温度对磨损量的影响．研究结果表明，Ni原子分数越高，合金硬度越高，口相含量越高，NiTi合金的抗磨损性能越好．     

真空电弧重熔NiTi形状记忆合金

对不同原料配比的NiTi形状记忆合金进行真空电弧重熔(VARM),利用化学元素分析仪、X射线衍射(XRD)仪、光学显微镜(OM)、扫描电子显微镜(SEM)以及X射线能谱仪(EDAX)等,分析合金中C,N,H的含量、物相以及显微组织.结果表明,随着NiTi合金边角料的增加,合金中的C,N,H含量逐渐增多.边角料的加入使合金中形成了Ni2Ti4O杂相,且随着NiTi合金边角料的增加,合金中Ni2Ti4O(511)衍射峰的强度逐渐降低,其铸态组织中基体B2相逐渐变为鱼骨状树枝晶,且质点状和线状的富钛第二相逐渐增多.对比分析认为重熔后合金中的杂质元素C,N,H和Ni2Ti4O杂相主要来源于边角料.     

Ni47Ti44Nb9形状记忆合金冲击过程形变机制行为分析

利用轻气炮装置在不同加载速率下对Ni47Ti44Nb9形状记忆合金进行了动态冲击加载实验。通过差示扫描量热仪(DSC)、X射线衍射仪(XRD)和透射电子显微镜(TEM)等先进的表征手段详细的探讨了冲击过程合金样品的物相转变机制和微观组织演化规律。利用阻抗匹配法对Ni47Ti44Nb9形状记忆合金在冲击过程受到的压力进行了计算。XRD结果表明：冲击后的样品未发生应力引发马氏体相变过程,在冲击过程中样品正面所受的冲击压力要明显大于背面。透射结果显示冲击后样品内部存在大量的微观缺陷,NiTi基体相与β-Nb粒子相均发生了明显的形变。     

Ni_(47)Ti_(44)Nb_9形状记忆合金冲击过程形变行为分析

利用轻气炮装置在不同加载速率下对Ni_(47)Ti_(44)Nb_9形状记忆合金进行了动态冲击加载试验。采用差示扫描量热仪(DSC)、X射线衍射仪(XRD)和透射电子显微镜(TEM)等先进手段对样品的形变行为进行了分析表征。探讨冲击过程合金样品的物相转变机制和微观组织演化规律。结果表明:冲击后样品内部存在大量微观缺陷,NiTi基体相与β-Nb粒子相均发生了明显的形变,但未发生应力引发马氏体相变过程,这可能是由于Ni_(47)Ti_(44)Nb_9合金马氏体相变温度较低以及β-Nb粒子对相变过程的阻碍作用引起的。     

激光选区熔化技术制备NiTi合金的研究进展与应用

NiTi合金作为一种典型的形状记忆合金,除了具有独特的形状记忆效应,还拥有优异的超弹性、生物相容性和力学性能,广泛应用于医学、机械、微电子等领域。然而,由于该合金延展性过高、加工硬化、低热导等问题,传统的切削方法加工工艺复杂、成本高,限制了其工程化应用。增材制造技术（Additive manufacturing, AM）又称3D打印技术,以其独特的一体化成形的技术优势,有效地改善了传统加工方法存在的问题。对此,国内外学者对激光选区熔化（SLM） 3D打印镍钛合金成形工艺进行了大量研究,并取得了丰硕成果。综述了近年来选区激光熔化镍钛的研究进展,简述了选区激光熔化和热处理工艺与镍钛合金的相变温度、组织结构、力学性能等映射关系,着重分析了SLM工艺参数对镍钛合金超弹性的影响规律,揭示了其影响机制,介绍了激光选区熔化镍钛合金的在医学领域的应用,并对未来NiTi合金的增材制造技术的发展提出了展望。     

NiTi形状记忆合金动态力学行为率-热效应实验测试

为准确掌握NiTi形状记忆合金在不同应变率、温度下的动态力学行为中的率-热效应,本文采用MTS809材料试验机与分离式霍普金森压杆实验装置开展了NiTi合金不同初始温度下的准静态单轴拉伸与不同应变率下的动态压缩实验。结果表明NiTi合金表现出应变率强化效应,其应力应变曲线包含双弹性阶段与双非线性变形阶段。相变起始应力、结束应力以及位错屈服应力均随着应变率增加而明显增大,母相弹性模量与马氏体弹性模量变化不明显。在准静态拉伸中其屈服应力与弹性模量随温度升高先线性增长继而线性减小,而两个温度阶段内的相变硬化率水平存在明显差异。     

Biocompatibility evaluation of NiTi SMA stent via intervenient therapy

1IntrouctlonNi Ti stent are medical devices i mplanted into human body via intervenient therapy,which are wovenout of Ni Ti memory alloy wire.Ni Ti stent for certain purposes are coated with silicon rubber and havelong-termosculation with organs such as esophagus,bile duct,trachea,blood vessel,etc.,which requiresexcellent biocompatibility as an i mportant criterion to ensure their safe and effective clinical application.The International Organization for Standardization has established the …     

Biocompatibility evaluation of NiTi SMA stent via intervenient therapy

NiTi shape memory alloy (SMA) stent with film are the long-term implanted medical devices which could be used in human's organ, such as esophagus, bile duct, urethra-prostate and blood vessel, by intervene therapy. It is very important to have a good biocompatibility for implanted device. According to standard ISO 10993, we completed biocompatibility evaluation of NiTi stent that included following tests: cytotoxicity, sensitization, genotoxicity, hemolysis and acute systemic toxicity, The results of tests qualify the NiTi stent, and provide an optimistic conclusion for the eventual use of NiTi stent as implanted medical devices.     

Relationship between mechanical property and microstructure of NiTi shape memory alloy

The relationship between mechanical property and microstructure of NiTi shape memory alloy has been studied. It was founded that with increasing prestrain the memory recovery rate decreased, but the recovery stress and the recovery strain increased first and then decreased. The recovery stress and the recovery strain reached maximum at about 11, prestrain. The TEM(Transmission Electron Microscope) results of the alloy indicated that the microstructures with different prestrain of the alloy had obvious characters. At 9, prestrain, the martensite anamorphosis of the alloy still presented self-cooperation configuration, and some martensites have become thick obvi ously because of tropism. When the prestrain was 11,, the martensite anamorphosis has become completely thick and tropism became consistent. As the prestrain increased to 13,, the microstructures of the alloy have become disordered, the tropism became inconsistent and the interface became blurry.     

Relationship between mechanical property and microstructure of NiTi shape memory alloy

The relationship between mechanical property and microstructure of NiTi shape memory alloy has been studied. It was founded that with increasing prestrain the memory recovery rate decreased, but the recovery stress and the recovery strain increased first and then decreased. The recovery stress and the recovery strain reached maximum at about 11% prestrain. The TEM(Transmission Electron Microscope) results of the alloy indicated that the microstructures with different prestrain of the alloy had obvious characters. At 9% prestrain, the martensite anamorphosis of the alloy still presented self-cooperation configuration, and some martensites have become thick obvi ously because of tropism. When the prestrain was 11%, the martensite anamorphosis has become completely thick and tropism became consistent. As the prestrain increased to 13%, the microstructures of the alloy have become disordered, the tropism became inconsistent and the interface became blurry.     

Relationship between mechanical property and microstructure of NiTi shape memory alloy

1IntroductionNi Ti shape memory alloy had superordinary superelasticity,shape memory property,biocompatibility,corrosion resistance and they have been applied extensively in aeronautics,aerospace,medical apparatusand instruments,and many other fields[1].The transformation behavior,shape memory effect,superelasticof Ni Ti shape memory alloy have been studied[2].It was founded that shape memory alloy had not onlyshape recovery but also recovery stress.However,studies of microstructure and the …     

Cu-Al-Mn系低温形状记忆合金的微结构研究

研究Cu-Al-Mn系低温形状记忆合金的微观组织结构和马氏体相交温度Ms的关系。结果表明，合金的Ms点随烈和Mn含量增加而显著降低。通过合适的成分设计，得到了Ms约为110K的Cu-Al-Mn系形状记忆合金。     

温度对Co-8.8Al-9.8W-1.5Ta合金γ′相形貌和结构的影响

为了研究温度对Co-8.8Al-9.8W-1.5Ta合金中强化相γ′相形貌结构的影响,利用SEM、XRD、TEM等表征手段,对不同固溶温度下制备的合金Co-8.8Al-9.8W-1.5Ta中强化相γ′-Co3(Al,W)相的形貌以及结构进行研究。结果表明:不同温度下制备的合金析出物相相同,主要包括γ-Co、γ′-Co3(Al,W)、Co3Ta和CoCx相;合金的制备温度不影响其物相组成,但对合金强化相的形貌有很大的影响。制备温度为1300℃时,合金中γ′相的组织形貌保持高度立方状,温度过高或过低时都使γ′相形貌偏向于圆形;固溶温度会影响合金中晶体取向和Ta元素的分布。固溶温度为1300℃时,γ′-Co3(Al,W)相中Al和W的原子比趋向于1,而温度过高或过低时,都会加大W在γ′-Co3(Al,W)相中的原子占比,并且Ta元素主要分布在强化相γ′上。     

低温形状记忆合金的相变温度变化

利用低温电阻法、差示扫描量热法(DSC)、物性测量系统(PPMS)等手段对马氏体相变温度为100 K左右的低温Cu-Al-Mn形状记忆合金的相变温度进行了测量,研究了不同热处理工艺下的相变点变化。结果表明,淬火后的记忆合金相变温度相比退火后明显降低,而不同的淬火速率也使Cu-Al-Mn形状记忆合金相变温度有所变化。