难熔钨基合金的研究开发及其产业化方向

综述了难熔钨基舍金的研究与开发现状及发展趋势；分析了难熔钨基合金的市场应用前景；并指出日趋成熟的新技术和新工艺，包括金属注射成形和挤压成形技术以及纳米复合粉末和细晶难熔钨合金的制备技术，必将成为21世纪难熔钨基合金的研究开发与高利润产品产业化方向。     

难熔钨基合金的研究开发及其产业化方向

综述了难熔钨基合金的研究与开发现状及发展趋势;分析了难熔钨基合金的市场应用前景;并指出日趋成熟的新技术和新工艺,包括金属注射成形和挤压成形技术以及纳米复合粉末和细晶难熔钨合金的制备技术,必将成为21世纪难熔钨基合金的研究开发与高利润产品产业化方向.     

热等静压在稀有难熔金属产品制备中的应用

简要介绍了热等静压技术的发展、设备原理、包套的选材与制作要求及数值模拟在热等静压技术中的应用,重点介绍了热等静压技术在稀有、难熔金属(钨、钼、钽、铌、铼及其合金)产品制备中的应用,以及热等静压处理对难熔金属微观组织及力学性能的影响研究。     

热等静压技术在高品质难熔金属靶材制备中的应用

随着电子信息产业的快速发展,市场对靶材的质量提出了越来越高的要求。热等静压技术作为一种材料成形及特殊热处理方法,经过多年发展,已成为制备高品质靶材的重要手段。简要介绍了热等静压技术的发展、设备工作原理以及难熔金属靶材的性能要求。重点介绍了热等静压技术在高品质难熔金属Mo、W、Cr及其合金靶材制备中的应用,以及热等静压工艺对其微观组织及溅射性能的影响。     

熔盐电脱氧法制备难熔金属及合金的研究进展

介绍了熔盐电脱氧法制备难熔金属及合金的基本原理和工艺,分析了熔盐电脱氧法的优势及目前存在的主要问题,归纳了采用熔盐电脱氧法制备难熔金属及合金的研究进展,指出了该制备工艺的发展趋势,并对其推广应用和实现大规模工业化前景等进行了讨论.     

机械合金化结合激光熔覆技术制备CoCrMoNbTi难熔高熵合金

采用机械合金化方法制备CoCrMoNbTi难熔高熵合金粉末，并通过激光熔覆技术成功制备出CoCrMoNbTi高熵合金涂层。研究了球磨时间对合金粉末组织形貌的影响，并利用X射线衍射仪、扫描电子显微镜和能谱仪等分析了高熵合金粉末和涂层的微观结构。结果表明，随着球磨时间的增加，单质金属的衍射峰按其熔点由低到高陆续消失。粉末微观形貌随球磨时间变化明显，粉末由原始状态被挤压成片状，片状粉末逐渐焊合在一起形成扁平状粉末颗粒。在球磨时间达到40 h时，粉末实现完全合金化，此时粉末形貌趋于球形且得到了极大的细化，粉末中各元素分布均匀，形成了稳定的单相体心立方固溶体结构。CoCrMoNbTi难熔高熵合金激光熔覆层成形质量良好，主要由体心立方固溶体和少量Cr₂Nb、Co₂Ti化合物组成，树枝晶组织细小致密。     

钨的冶金及其加工技术

简要综述了钨的冶金和加工技术。除了用于制备高纯金属以及单晶等场合之外,钨及其合金的制备仍以粉末冶金方法为主,但近些年来在纳米钨粉的制备、掺杂钨合金的研究、钨合金的注射成形和复合材料的制备方面有很快地发展。     

一种粉末冶金制备钼合金TZM的方法

一种粉末冶金制备钼合金TZM的方法,涉及一种采用粉末冶金工艺制备难熔金属合金方法。其特征在于是选用费氏粒度在5～10μm,最大颗粒不大于10μm的氢化钛和氢化锆颗粒,采用粉末冶金的方法制备TZM钼合金的。本发明的采用粉末冶金工艺制备钼合金TZM的方法,通过添加颗粒细小的合金元素粉末;由于第二相颗粒尺寸小,使烧结过程扩散均匀;提高了材料组织的均匀性,     

高纯稀有金属材料

综述了各种高纯稀土难熔、稀散金属及其合金的功能、制备方法、应用现状及其前景。     

熔盐电解固态氧化物制备难熔金属及合金的最新进展

介绍了熔盐电解固态氧化物制备金属(FFC法)的基本原理,并综述了利用FFC法制备难熔金属及合金的最新进展,分析了FFC法的优点及目前存在的主要问题,指出如果FFC法的电解速度和电流效率得以提高,电解固态氧化物直接制备金属及合金将具有很好的工业化前景.     

Contact Interaction of Niobium and Iron Single Crystals with Low-Melting Metals

We have used the sessile drop method to study interfacial properties in low-melting metal – niobium and iron single crystal systems. The study was conducted on an automated apparatus which allowed us to photograph the drop and to transfer an image to a computer for further processing. We present data on the effect of temperature on the surface tension and contact angles for wetting of niobium single crystal substrates by pure metals (silver, lead, and indium) and by lead – silver, silver – copper alloys and also for wetting of an iron single crystal by lead.     

The influence of cobalt,tantalum, and tungsten on the elevated temperature mechanical properties of single crystal nickel-base superalloys

The influence of composition on the tensile and creep strength of [001] oriented nickel-base superalloy single crystals at temperatures near 1000 °C was investigated. Cobalt, tantalum, and tungsten concentrations were varied according to a matrix of compositions based on the single crystal version of MAR-M247.* For alloys with the baseline refractory metal level of 3 wt pct Ta and 10 wt pct W, decreases in Co level from 10 to 0 wt pct resulted in increased tensile and creep strength. Substitution of 2 wt pct W for 3 wt pct Ta resulted in decreased creep life at high stresses, but improved life at low stresses. Substitution of Ni for Ta caused large reductions in tensile strength and creep resistance, and corresponding increases in ductility. For these alloys with low Ta plus W totals, strength was independent of Co level. The effects of composition on properties were related to the microstructural features of the alloys. In general, high creep strength was associated with high levels ofγ′ volume fraction,γ-γ′ lattice mismatch, and solid solution hardening.     

Improvement of top casting of high-alloy steel into a mold

The problems related to improving the process of top casting of complexly alloyed and high-alloy steels and alloys are considered. To increase the ingot surface quality and the ingot-to-product yield, a new method of top casting of steels and alloys is proposed. In this method, a floating shield made of a light refractory material is placed in a mold and protects the mold surface against metal splashes.     

Corrosion of Refractory Alloys in Molten Lithium and Lithium Chloride

Several refractory materials have been considered over the years as containment material for lithium and lithium halides. Surface modified refractory metals are being extensively investigated for containment of reactive metals, radionuclides and their compounds. An overview of experimental observations and results of liquid lithium corrosion of selected engineering refractory materials are presented. The nature of the degradation and its mechanism has been explained. The influence of temperature, microstructure, stress, impurities and service time on the corrosion behavior for various refractory alloys have been discussed. Selection rules for materials of containment for liquid lithium and lithium compounds have been suggested. Recent experimental observations on the behavior of tantalum and niobium-based refractory metal alloys in a specific molten salt environment comprising LiCl/Li₂O/Li/Li₃N at 725°C have been included in an effort to select suitable materials for molten salt equipment. It has been observed that oxygen contamination is particularly harmful for the refractory metal alloys where as nitrogen is deleterious to iron-based alloys.     

Corrosion of Refractory Alloys in Molten Lithium and Lithium Chloride

Abstract

Several refractory materials have been considered over the years as containment material for lithium and lithium halides. Surface modified refractory metals are being extensively investigated for containment of reactive metals, radionuclides and their compounds. An overview of experimental observations and results of liquid lithium corrosion of selected engineering refractory materials are presented. The nature of the degradation and its mechanism has been explained. The influence of temperature, microstructure, stress, impurities and service time on the corrosion behavior for various refractory alloys have been discussed. Selection rules for materials of containment for liquid lithium and lithium compounds have been suggested. Recent experimental observations on the behavior of tantalum and niobium-based refractory metal alloys in a specific molten salt environment comprising LiCl/Li₂O/Li/Li₃N at 725^°C have been included in an effort to select suitable materials for molten salt equipment. It has been observed that oxygen contamination is particularly harmful for the refractory metal alloys where as nitrogen is deleterious to iron-based alloys.     

热压法制备的(Mo1-xMbx)5Si3合金组织及抗腐蚀性能

以Mo粉、Nb粉、Si粉为原料,采用热压法制备(Mo<,1-x>Mb<,x>)<,5>Si<,3>(x=0,0.2,0.4)难熔金属硅化物合金,利用电化学测试及盐酸浸泡腐蚀实验,研究该合金在浓度为1 mol/L的HCl溶液中的腐蚀行为以及Nb含量对合金组织和耐蚀性的影响.结果表明,随Nb含量增加,(Mo<,1-x>Mb...     

The influence of cobalt,tantalum, and tungsten on the microstructure of single crystal nickel-base superalloys

The influence of composition on the microstructure of single crystal nickel-base superalloys was investigated. Co was replaced by Ni, and Ta was replaced by either Ni or W, according to a matrix of compositions based on MAR-M247. Substitution of Ni for Co caused an increase inγ′ solvus temperature, an increase inγ-γ′ lattice mismatch, and the precipitation of W-rich phases in the alloys with high refractory metal levels. Substitution of Ni for Ta caused large decreases inγ′ solvus temperature,γ′ volume fraction, andγ-γ′ lattice mismatch, whereas substitution of W for Ta resulted in smaller decreases in these features. For the alloys withγ′ particles that remained coherent, substitution of Ni for Co caused an increase inγ′ coarsening rate. The two alloys with the largest magnitude of lattice mismatch possessedγ′ particles which lost coherency during unstressed aging and exhibited anomalously low coarsening rates. Creep exposure at 1000 °C resulted in the formation ofγ′ lamellae oriented perpendicular to the applied stress axis in all alloys.     

Re含量对单晶高温合金组织和拉伸性能的影响

为优化一种单晶高温合金中的Re含量,在真空定向凝固炉中制备了3%Re和5%Re的镍基单晶高温合金,热处理后分别在980 ℃长期时效400、800、2 000 h,测试合金热处理后1 100 ℃拉伸性能,采用JMatPro软件计算了合金相图,通过光学显微镜、扫描电镜和能谱仪研究Re含量对合金枝晶组织,热处理组织和980 ℃时效400、800、2 000 h的组织和1 100 ℃拉伸性能的影响。结果表明,随着单晶高温合金中Re含量增加,一次枝晶间距轻微减小,共晶的体积分数升高;γ′相尺寸下降,立方化程度增加;不同Re含量合金时效800 h后无TCP相析出,时效2 000 h后有TCP相析出,随着Re含量增加,TCP相析出量增加。合金组织稳定性随着Re含量增加而降低。随着Re含量增加,合金的高温拉伸性能显著提高。      

The heat resistance of structural materials in modern engineering

Summary Factors determining heat resistance and refractoriness of primarily metal powder heat-resistant compositions were considered, with special attention to the strength of the interatomic bond and possible methods of its evaluation. On the basis of calculation of the root mean square displacement of atoms in the crystal lattice of heat-resistant metals and compounds, a scheme was proposed for the arrangement of many metals, on the principle of their capacity for use as a base in production of heat-resistant alloys. In estimating heat resistance of refractory compositions, we suggested taking the indices of relaxation capacity as a basis. Technological methods were outlined for producing heat-resistant compositions by use of materials possessing especially high interatomic bond strength. The principal factors characterizing the scale-resistance of refractory compositions were defined.     

难熔高熵合金:制备方法与性能综述

从加工方法、微观结构以及各类性能三方面介绍了难熔高熵合金(Refractory high-entropy alloys,RHEAs),最后对难熔高熵合金的发展和未来进行了展望。以MoNbTaVW为代表的难熔高熵合金在高温下表现出优于传统镍基高温合金的压缩屈服强度,且屈服强度随温度的变化更加缓慢,高温力学性能优异;以MoNbTaVW、MoNbTaTiZr、HfNbTiZr等为代表的难熔高熵合金,与商用高温合金、难熔金属、难熔合金以及工具钢相比,展现出更优的耐磨性能。以W₃₈Ta₃₆Cr₁₅V₁₁合金为代表的难熔高熵合金在辐照后,除了析出小颗粒第二相外,不存在位错环缺陷结构,抗辐照性能优异。提出了难熔高熵合金未来发展的两大方向:建立高通量的实验和计算方法继续探索更多的难熔高熵合金组成和结构模型;探索多场耦合环境下难熔高熵合金的服役行为。