镍的电子束熔炼提纯研究

高纯镍是制造半导体集成电路及微电子行业用电子薄膜材料的原材料。采用电子束熔炼方法制备高纯镍,研究了一次和二次电子束熔炼对高纯镍锭纯度、表面质量和内部铸造缺陷的影响。通过对铸锭宏观形貌的观察和杂质含量的化学分析,发现一次熔炼可将原材料提纯至99.99%,但铸锭仍存在较多宏观铸造缺陷;而二次熔炼充分去除了杂质和气体元素,如Al,Fe,Cu和C,N,O等,最终使镍锭纯度提高至99.995%以上且内部连续一致无集中缩孔、疏松和气孔等缺陷。通过对镍电子束熔炼过程中杂质元素和基体镍的蒸气压的理论计算对比,和对杂质去除率的理论计算,说明了杂质从镍基体分离的方式并验证了化学成分检测的杂质实际去除率。     

电子束选区熔化成形Nb521合金微观组织与性能分析

采用电子束选区熔化技术制备Nb521合金,研究其致密化成形工艺。通过对成形试样的组织、物相、显微硬度、室温拉伸性能的检测与分析,探讨了电子束选区熔化成形Nb521合金的机理。结果表明,电子束选区熔化成形过程中,电子束熔化电流及速度的合理匹配,是得到表面质量及内部质量优异的成形样品的基础;电子束能量密度为340 J/mm3时,样品的密度达到8.78～8.79 g/cm3; Nb521合金显微组织沿沉积方向呈柱状晶,晶粒沿(200)晶面有较强的择优生长取向;成形样品中除Nb基体相外,还存在少量的Nb2C与Zr C碳化物析出;样品室温抗拉强度达到384 MPa,屈服强度为307 MPa,断后延伸率为16.5%;显微硬度处于1 500～1 700 MPa之间,无各向异性。     

Characterization of Ni-Based Superalloy Built by Selective Laser Melting and Electron Beam Melting

Alloy718 specimens built by selective laser melting (SLM) and electron beam melting (EBM) were comparatively examined. The higher cooling rate resulted in a high dislocation density and interdendritic precipitates, which brought about inferior creep properties in SLM alloys. However, a low dislocation density, distributed δ precipitates and a strong 〈001〉 texture were observed in the EBM material. As a result, the creep life of the direct-aged EBM specimen approached 1100 hours and was comparable to that of conventional cast-and-wrought alloys at 650 °C.     

Preparation of High-Purity Tin by Zone Melting

High-purity tin is widely used in advanced technologies such as aerospace, electronic information, and nuclear industry. It has become a key material supporting the development of human science and technology innovation. However, there are few studies on the preparation methods of high purity tin. A novel technique was developed to purify 99.99682% tin by zone refining in an argon atmosphere. The impacts of zone melting conditions, such as the segregation coefficient, zone melting rate, and the number of zone melting passes, on the purity of refined tin were experimentally studied. The results showed that the segregation coefficients of Ag, Al, As, Bi, Ca, Cu, Fe, Ni, Pb, Au, Co, and Zn were less than 1, and the segregation coefficient of Sb was greater than but close to 1. Zone melting rates had an obvious effect on zone refining, while the number of passes had little effect. The 99.99682% purity tin was refined into 99.99906% purity tin under the optimized conditions at a zone melting rate of 0.6 mm/min and after 10 cycles of zone melting and cooling.     

电子束熔炼技术及其应用

本文介绍电子束熔炼技术的发展及现状,阐述了几种电子束熔炼工艺的原理、设备和用途,详细介绍了电子束冷床炉在钛工业上的应用.     

Electron Beam Melting of High Niobium Containing TiAl Alloy: Feasibility Investigation

Third generation γ‐TiAl alloys with a high niobium content, Ti–(47–48)Al–2Cr–8Nb, were processed by electron beam melting (EBM). This near‐net‐shape additive manufacturing process produces complex parts according to a CAD design. The starting powder is deposited layer by layer on the building table and selectively melted to progressively form the massive part. The EBM parameters such as layer thickness, melting temperature, scanning speed, or building strategy were set up to minimize porosity. The chemical composition of the built material is similar to the composition of the base powder despite a slight evaporation of aluminum and reveals a neglectable oxygen pick‐up. The very fine equiaxed microstructure resulting after EBM can be then set up by heat treatment (HT). According to the HT temperature in particular, an equiaxed microstructure, a duplex microstructure with different lamellar ratio and a fully lamellar microstructure is obtained. Not only test bars have been produced but also complex parts such as demo low pressure turbine blades.     

电解精炼-区域熔炼法制备高纯铟的研究

采用电解精炼 区域熔炼法 ,获得了 99 9999%高纯铟。从理论上探讨了采用区域熔炼法进一步提高铟的纯度的原理。采用In2 (SO4 ) 3～H2 SO4 体系 ,控制电解液pH为 2～ 3 ,In含量 80～ 10 0g·L- 1 ,电流密度 80～ 10 0A·m- 2 ,温度为 2 0～ 3 0℃ ,进行一次电解精炼 ,可得到纯度接近 99.999%的高纯铟。以电解精炼铟为原料进行区域熔炼 ,对熔体进行磁力搅拌 ,控制较低的区熔速度 ,可获得 99.9999%以上的高纯铟     

Preparation of High-Purity Cobalt by Anion-Exchange Separation and Plasma Arc Melting

High-purity Co was prepared with valence-controlled anion-exchange separation, oxidation refining using plasma arc melting, and H₂-Ar plasma arc melting on a pilot scale. The result of a laboratory-scale experiment indicated that the slower flow rate is more effective to remove the impurities by anion-exchange separation. However, the separation efficiency is reduced by scaling up the column from the laboratory to pilot scale. The discussion of the decrease in the separation efficiency implies that the distribution coefficient increases as the concentration of the adsorbate is lowered, but a reduced slower flow rate might increase the final purity of Co. In addition to anion-exchange separation, Co oxidation refining using plasma arc melting was useful. Consequently, a high-purity Co of 99.9998 pct by mass excluding gaseous elements was prepared, which represents the highest purity reported.     

电子束冷床熔炼TC4合金的热平衡分析

通过对TC4合金电子束冷床熔炼过程热平衡的计算和实验验证,为制定合理的熔炼工艺提供计算依据。计算结果表明,维持冷床液态熔池表面125℃过热和结晶坩埚内100℃过热的条件下,随着熔炼速度从60kg／h增加到150kg／h,冷床内所需热量稍微增加,熔炼原料的功率明显增加,而凝固坩埚内所需热量有所降低。在提高冷床内和坩埚内的过热度时,其所需的热量都增加。     

3200kW电子束冷床炉熔炼纯钛电子枪工艺参数设置

电子束冷床炉熔炼是目前较先进的钛及钛合金熔炼技术,是生产大型优质钛锭的重要熔炼方式。本研究采用颗粒状海绵钛为原料,以垂直进料的方式熔炼大型纯钛扁锭,对电子束冷床炉熔炼区、精炼区、结晶器的4支电子枪工艺参数的设置进行了分析并制定了电子枪工艺参数。通过为期1个月的纯钛扁锭熔炼试验验证,结果表明,制定的工艺参数能够稳定生产纯钛铸锭,且熔炼速度可稳定在1 500 kg/h,挥发损失控制在3%以内,铸锭表面质量良好,化学成分均匀,成品率提高,有效降低了熔炼成本。     

TC16钛合金板材冷轧工艺及组织性能研究

进行了TC16钛合金板材多道次冷轧试制,利用光学显微镜、 扫描电镜和X射线衍射等手段研究了变形量对冷轧板材微观组织与力学性能的影响.结果表明:α+β两相TC16钛合金板材冷轧加工是可行的,其极限冷变形量达到79％,冷轧板材表面无裂纹.大幅度冷轧变形后,TC16钛合金组织为分布均匀的纤维状结构,且存在极少量未充分变形的α...     

Mechanism of Primary Purification in Zone Melting of Boron-Containing Powder Materials

We have established the regular behavior of the change in chemical composition and grain size of refractory material when sintered in the presence of a moving liquid phase under conditions including a high temperature gradient and continuous heating, and on this basis we propose a mechanism for primary purification to remove impurities from boron-containing powder materials during zone melting. We have shown that the degree of purification depends on the completeness of recrystallization of particles of the refractory material through the solvent melt, and is determined by the physical and processing properties of the original powders, the temperature and time parameters for the zone melting, the structure of the phase diagram, and the kinetics of diffusional interaction processes in the system refractory material solvent for the impurities.     

Comparison of Microstructures and Mechanical Properties for Solid and Mesh Cobalt-Base Alloy Prototypes Fabricated by Electron Beam Melting

The microstructures and mechanical behavior of simple, as-fabricated, solid geometries (with a density of 8.4 g/cm³), as-fabricated and fabricated and annealed femoral (knee) prototypes, and reticulated mesh components (with a density of 1.5 g/cm³) all produced by additive manufacturing (AM) using electron beam melting (EBM) of Co-26Cr-6Mo-0.2C powder are examined and compared in this study. Microstructures and microstructural issues are examined by optical metallography (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD), while mechanical properties included selective specimen tensile testing and Vickers microindentation hardness (HV) and Rockwell C-scale hardness (HRC) measurements. Orthogonal (X-Y) melt scanning of the electron beam during AM produced unique, orthogonal and related Cr₂₃C₆ carbide (precipitate) arrays (a controlled microstructural architecture) with dimensions of ~2 μm in the build plane perpendicular to the build direction, while connected carbide columns were formed in the vertical plane, parallel to the build direction, with microindentation hardnesses ranging from 4.4 to 5.9 GPa, corresponding to a yield stress and ultimate tensile strength (UTS) of 0.51 and 1.45 GPa with elongations ranging from 1.9 to 5.3 pct. Annealing produced an equiaxed fcc grain structure with some grain boundary carbides, frequent annealing twins, and often a high density of intrinsic {111} stacking faults within the grains. The reticulated mesh strut microstructure consisted of dense carbide arrays producing an average microindentation hardness of 6.2 GPa or roughly 25 pct higher than the fully dense components.     

悬浮熔炼制备新型稀土金属间化合物

利用冷坩埚悬浮熔炼法制备具有严格化学计量比的二元稀土金属间化合物(RM)的原理与过程,对所制备的RM进行了材料表征和力学性能测试,并通过分析扫描断口以及力学性能数据,探讨了RM在室温下的断裂机制.     

电子束冷床熔炼参数对熔池表面温度的影响

使用M9100图像高温仪精确测定了TC4合金电子束冷床熔炼时坩埚和冷床熔池表面的温度.结果表明,结果表明,熔炼工艺参数如熔化速度、熔炼功率、电子束扫描方式和扫描频率都会对熔池表面温度产生剧烈影响.     

Rare-Earth Functional Films Prepared by Ion Beam Epitaxy

Rare-Earth Functional Films Prepared by Ion Beam Epitaxy