热等静压法制备高立方织构的镍基合金复合基带

采用热等静压(HIP)法制备芯层为Ni-12％W(Ni12W,摩尔分数)合金、外层为Ni-5％W(Ni5W,摩尔分数)合金的Ni5W/Ni12W/Ni5W 3层复合初始坯锭:采用压延辅助双轴织构技术(RABiTSTM)通过直接冷轧及再结晶退火获得Ni5W/Ni12W/NiSW复合基带;采用X射线四环衍射技术(XRD)及背散射电子衍射技术(EBSD)对复合基带表面冷轧及再结晶织构进行分析.结果表明:冷轧复合基带表面形成较强的铜型形变织构,再结晶退火后复合基带表面形成锐利的立方织构,其立方织构含量达到99.1％(≤10°),与商业用Ni5W合金基带水平相当.     

涂层导体用Ni9W合金基带再结晶及强立方织构的形成研究

采用X射线四环衍射技术对比分析了通过冷轧和轧制中间热处理制备的2种Ni-9.3at%W(Ni9W)合金基带的轧制织构和再结晶织构,研究了不同Ni9W合金基带在热处理过程中轧制织构向再结晶织构的演变。其次,采用背散射电子衍射(EBSD)技术对以上2种Ni9W合金基带的微观组织和立方织构进行了表征。结果表明,与传统冷轧Ni9W合金基带的轧制织构相比,经轧制中间热处理后其轧制织构中S取向和Copper取向的含量增加、Brass取向的含量减少,使其轧制织构的类型介于Brass型轧制织构与Copper型轧制织构之间。2种Ni9W合金基带经低温回复后,其轧制织构含量均有一定的增加;另外,再结晶过程中轧制织构的含量均迅速降低,但立方取向的含量并没有明显增加,而是出现大量的随机取向,Ni9W的再结晶具有了连续再结晶的特征,这也是导致Ni9W合金基带较难形成立方织构的一个主要原因。虽然经过轧制中间热处理后Ni9W合金基带在初始再结晶完成后并没有形成一定强度的立方织构,但其立方取向的含量仍然能在进一步热处理过程中通过立方取向晶粒的长大而得到加强。最后,采用轧制中间热处理制备的Ni9W合金基带经两步高温热处理后其立方织构的含量达到84.5%(15°)。     

轧制中间热处理温度对Ni7W/Ni12W/Ni7W复合基带组织及织构的影响

采用压延辅助双轴织构技术制备了涂层导体用Ni7W/Ni12W/Ni7W复合基带。复合基带轧制形变过程加入3次不同温度的轧制中间热处理优化其形变组织。采用X射线衍射及背散射电子衍射技术分析了复合基带轧制过程中表面及截面的形变及回复组织,以此探索轧制中间热处理温度对Ni7W/Ni12W/Ni7W复合基带形变及立方织构形成过程的影响机制。结果显示,经600S°C/60Smin轧制中间热处理后的复合基带在较低的再结晶温度下获得了95% (<10°)的高立方织构含量。晶体取向分布图表明该中间热处理温度下复合基带回复及初始再结晶组织中立方取向的晶粒含量都更高;不同取向间点对点的晶体取向差分析证实了立方取向晶粒较大的晶界角,这使立方取向在回复及初始再结晶过程具有高的界面迁移率,从而促进了后续再结晶过程强立方织构的形成。     

超细晶纯钛材电化学抛光表面生物相容性研究

制备具有高强度、低磁性的双轴织构金属基带是获得高性能涂层超导体的基础.目前,传统的Ni5at％W (Ni5W)合金基带已经可以工业化生产,但其立方织构的形成机理尚不明确.以真空熔炼方法制备的大形变量(约99％)冷轧Ni5W合金基带作为研究对象,采用EBSD技术进行表征,系统的研究了其形变织构的演变、再结晶形核和晶粒长大等过程.研究发现,Ni5W合金基带的形变织构为典型的铜型轧制织构;在再结晶初期阶段,立方取向晶粒优先在靠近基带表层的区域形核,且具有一定的尺寸优势,其形核在厚度方向上表现出梯度分布的特点;在完全再结晶阶段,立方取向的晶粒通过“尺寸优势”和“取向长大优势”逐渐吞并其它取向的晶粒,形成强的立方织构.     

放电等离子烧结法制备涂层导体用Ni合金复合长带

采用放电等离子烧结技术(SPS)制备出表层为Ni-5%W(摩尔分数)合金、芯层为Ni-12%W(摩尔分数)合金的复合坯锭,经热轧和冷轧后获得长度为10 m的复合基带.结果表明:冷轧基带界面连接性良好,能够满足大变形量冷轧工艺的要求.对复合基带的厚度及织构均匀性分析表明,在全长度范围内基带的厚度为(75±3) μm,其外层立方织构含量均在97%(＜10°)以上,与商业化Ni5W基带水平相当.同时,对其力学性能与磁性能进行分析,结果表明复合长带的屈服强度为240 MPa,饱和磁化强度仅为Ni5W基带的40%.采用复合坯锭路线在规模化生产高性能复合基带方面具有一定的应用潜力.     

熔炼路线制备Ni5W合金基带立方织构形成过程的研究

制备具有高强度、低磁性的双轴织构金属基带是获得高性能涂层超导体的基础。目前,传统的Ni5at%W(Ni5W)合金基带已经可以工业化生产,但其立方织构的形成机理尚不明确。以真空熔炼方法制备的大形变量(约99%)冷轧Ni5W合金基带作为研究对象,采用EBSD技术进行表征,系统的研究了其形变织构的演变、再结晶形核和晶粒长大等过程。研究发现,Ni5W合金基带的形变织构为典型的铜型轧制织构;在再结晶初期阶段,立方取向晶粒优先在靠近基带表层的区域形核,且具有一定的尺寸优势,其形核在厚度方向上表现出梯度分布的特点;在完全再结晶阶段,立方取向的晶粒通过"尺寸优势"和"取向长大优势"逐渐吞并其它取向的晶粒,形成强的立方织构。     

再结晶退火过程中Ni5W合金基带的结构转变

研究了YBCO涂层导体用的立方织构Ni5W合金基带在1 000℃下快速加热和快速冷却处理时的结构变化.X射线检测结果表明,热处理时间小于20min时,和立方织构百分数大小有关的I200/I111强度比随热处理时间的增加而快速增加.热处理时间从1 min增加至20 min,I200/I111强度比从10快速增加至103数量级.当热处理时间大于20min之后,I200/I111强度比随热处理时间的增加而明显降低.当热处理时间超过10 min之后,伴随I200/I111强度比的增加,Ni5W合金的晶格常数变小.实际上,Ni5W合金基带中的立方织构形成非常迅速,在1 000℃下,热处理10～20 min,样品中的立方织构百分数已接近100%.EBSD对样品进行立方织构百分数测量的结果和XRD分析结果非常一致,而且,EBSD的测量结果表明,对应立方织构百分数的增加,晶粒尺寸突然增加.本研究得到了较合适的加工和热处理制度,并用这样的制度制作出了具有锐利立方织构的Ni5W合金基带.     

复合基带外层Ni5W再结晶织构演变的研究

采用X射线四环衍射技术和背散射电子衍射技术,对具有多层结构的NiW合金复合基带外层Ni5W(at%)的形变织构和再结晶织构进行了研究。研究发现,梯度分布的形变织构和多层材料之间的扩散是决定复合基带外层Ni5W织构演变的两个主要因素。这为进一步研究金属合金复合材料各层之间的织构形成及其关联性奠定了基础。     

高强度低磁性织构金属NiW合金基带的研究

介绍了几种制备高强度、低磁性、表面具有锐利双轴织构的金属NiW基带的思路和工艺路线,并表征了其性能。结果表明,所获得的Ni7W以及一系列Ni基复合基带的立方织构分别同商业的Ni5W基带相当或较好,而强度和磁性均较Ni5W基带有较大改善。而且其制备思路和手段作为一种行之有效的方案,也为进一步优化NiW合金基带乃至其他合金基带的性能提供了依据。     

涂层导体用Ni-7%W合金基带的织构分析

采用先进的放电等离子烧结技术(SPS)制备Ni7W合金初始坯锭,通过优化高能球磨和烧结工艺以及后续和热处理工艺制备出高度立方织构的Ni7W合金基带.利用电子背散射衍射(EBSD)技术对Ni7W合金基带的晶粒取向、晶界特征等信息进行采集和分析,对其织构进行了表征.该基带无需抛光,即可获得高花样质量的电子背散射衍射图像.EBSD测试结果表明:该Ni7W基带表面10°以内立方织构晶粒质量分数高达99.4%,10°以内晶界长度质量分数为93.6%,具有高质量的立方织构.     

Characterization and properties of an advanced composite substrate for YBCO-coated conductors

Thin, biaxially textured Ni5W/Ni12W/Ni5W composite substrates for coated conductor applications have been fabricated. The particularity of this three-layer composite configuration resides in the elemental diffusion between the outer layer and the core layer. Due to the migration of elemental W, the diffusion layer in the as-annealed substrate becomes broader than that of the as-rolled substrate. The obtained tape has a sharp cubic texture on the Ni5W outer layers, and the volume fraction of cubic grains exceeds 98.8% (<10°) at the outer surfaces. In situ electron backscatter diffraction strain–stress analysis shows that the high-quality cubic texture was stable until elongations as high as 2%. The yield strength of the composite substrate approaches 240 MPa and its saturation magnetization at 77 K has been strongly reduced with respect to pure Ni and Ni5W substrates. The present results demonstrate that this advanced three-layer substrate is suitable for the epitaxial growth of the LZO buffer layers.     

LZO covered Cu-based substrates

A Cu-based substrate has been made by electrodepositing a Ni layer on top of cube-textured Cu tape obtained by an alternating mechanical/thermal treatment. It could be found that the volume fraction of the cube texture component of Cu tapes increased with the annealing temperatures for an optimized rolling process. When the annealing temperature is at 800 °C, the sharpness of cube texture is best. In order to fabricate LZO films on the Cu-based substrate, a Ni layer was added on top of the Cu tape by electroplating. The thickness of Ni layer not only affects the texture sharpness of the substrate, but also affects its thermal stability of texture. A thickness of 15 μm was efficient to protect the Cu tapes. Fabricating well bi-axially textured LZO film on this bi-metallic substrate proves that this new Cu-based substrate is a good choice for coated conductor.     

Development of high strength and strongly cube textured Ni-4.5% W/Ni-15% Cr composite substrate for coated conductor application

The development of thin, mechanically stronger and highly cube textured substrates is of great technological importance for increasing the engineering current density of the coated conductors. Nickel is a suitable substrate for this in view of its ability to form strong cube texture after heavy rolling and annealing and its excellent oxidation resistance. However, nickel is very soft (yield strength ~40 MPa) and this limits the processing to thin tapes. The ferromagnetism of Ni is also undesirable for ac application of coated conductors in magnetic fields. In the present paper we report on the development of Ni-4.5 at.% W/Ni-15 at.% Cr composite substrates of 80 and 40 μm thickness with strong cube texture, high yield strength (~200 MPa) and reduced magnetisation losses. The strong cube texture was obtained through an optimised two-step recrystallisation annealing following heavy cold working. It was found that the presence of non-cube texture forming alloy (Ni-15% Cr) in the inner core of the composite had no adverse affect on the growth of cube textured grains on the surface (Ni-4.5% W) even at a low substrate thickness of 40 μm. A significant improvement in the texture/misorientation distribution was observed in the CeO₂ buffer layer deposited on the composite substrate.     

Highly reinforced and cube textured Ni alloy composite substrates by a hybrid route

A Ni-based tri-layer composite substrate designed as a substitute for traditional substrate architecture, was obtained by sintering together two Ni–5 at.%W layers on both sides of a metallurgically prepared powder Ni–12 at.%W inner layer. An advanced sparking plasma sintering technology was used, followed by cold rolling and annealing. The composite substrates obtained have a very sharp cube texture on the Ni–5 at.%W outer layer and the yield strength exceeds 320 MPa, while the magnetization behaviour was dramatically reduced. These properties render these tri-layer substrates suitable for the epitaxial growth of buffer layers for coated conductor applications.     

形变细化晶粒和润滑轧制对Ni-9.3at.%W合金基带立方织构形成的影响

采用光学显微镜(OM)、X射线四环衍射(XRD)技术、电子背散射衍射(EBSD)技术分析研究了形变细化晶粒、润滑轧制对Ni-9.3at.%W(Ni9.3W)合金基带立方织构形成的影响。结果表明,采用形变细化晶粒的方法能有效提高Ni9.3W合金基带的立方织构含量,并且随着初始形变量的增加,晶粒细化程度越大,立方织构含量越高,采用优化的形变细化晶粒工艺使得Ni9.3W合金基带立方织构含量提高了9.8%。另外,增加形变细化晶粒后的轧制总变形量,立方织构含量进一步提升了24.7%,根据以上结果,确定了初始坯锭制备阶段的参数。在此基础上,研究了轧制变形的润滑与非润滑对立方织构形成的影响,相比非润滑轧制而言,采用润滑轧制,轧制织构中获得了较多的S取向与Copper取向,经再结晶退火后,润滑轧制基带的立方织构含量比非润滑轧制基带的立方织构含量高9.6%,达到了86.7%(<15°),而且孪晶界数量、小角度晶界含量均要优于非润滑轧制,说明润滑轧制对立方织构形成有着积极的影响。