闪光对焊采用镍钛铬系电极合金的研究

本文论述了闪光对焊采用镍钛铬电极合金的研制过程:在铜基中加入适量的Ni和Ti元素,通过固溶和时效热处理形成弥散颗粒的金属化合物Ni_3Ti,提高了电极合金的高温强度和抗粘性能,取得了良好的性能和使用效果。     

颗粒弥散钛基复合材料

颗粒弥散钛基复合材料为了克服钛的低耐磨性，低弹性模量和低耐热性等固有缺点，利用各种高硬度高弹性模量的陶瓷颗粒在钛基体中的适当弥散制成复合材料是很有效的方法。近年来开发成功一种全新型的复合方法，即是利用自耗电极式真空电弧重熔（ＶＡＲ）进行各种陶瓷颗粒的...     

层状复合基体材料电极的性能研究

利用Ti-Al、Ti-Cu层状复合材料替代传统钛电极单一钛基体,对比研究其涂层电极与传统钛涂层电极的电化学性能差异,进行电极基体材料的导电性测试、涂层表面的微观形貌观察和线性伏安曲线(LSV)、循环伏安曲线(CV)等电化学分析.结果表明:采用钛-铝、钛-铜复合材料对基体材料进行改进,提高了电极的导电性,并有效地提高了极板的电化学性.     

三栅极离子渗镀技术及其应用

利用三栅极离子渗镀方法在钛基和石墨基上制备出新型阳极材料; 利用XRD、GDS等测试手段对这种阳极电极进行了表征; 观察了电极1mol/LH2SO4溶液60℃时的电解寿命; 测定了电极的极化曲线及动力学参数, 并与同类其他电极进行了比较.结果表明: 在钛基上用这种新型方法制备的电极具有一些特殊的性能和可观的应用前景.     

钛基二氧化铅电极的研究进展

综述了国内外钛基二氧化铅电极的制备方法,包括电沉积法、热分解法、热浸法、溶胶凝胶法;分析了添加某些固体颗粒及离子对钛基二氧化铅电极改性的影响.结合相关学者最新的研究成果,展望了未来钛基二氧化铅电极材料的发展趋势.     

表面渗钛的镀锌钢板点焊电极寿命试验研究

对Cr-Zr-Cu合金的镀锌钢板点焊电极进行了表面渗钛处理，通过点焊电极寿命试验观测了表面渗钛处理前后镀锌钢板点焊的表面质量和电极端面状况。试验结果表明，采用表面渗钛可以提高镀锌钢板点焊电极的耐磨性和热稳定性，从而延长了电极的寿命。     

柔性钛电极电火花合成TiN涂层

文中提出一种利用柔性钛电极在钛合金TC4表面合成TiN涂层以改善工件表面性能的新方法.在加工中利用柔性钛电极与钛合金TC4表面进行电火花放电,同时通过钛电极内部向加工区域通入氮气,利用电火花放电能量在工件表面反应生成TiN涂层.测量其表面硬度并利用SEM,XRD等手段对其涂层微观形貌和组分进行测试.结果表明,在TC4工件表面制备出了TiN强化涂层,涂层致密、均匀、连续;TiN涂层厚度超过1 mm;涂层主要由TiN强化相组成,显微硬度高达1859.6 MPa;涂层表面的放电坑大而浅且存在刮削痕迹,柔性钛电极丝对TiN涂层有较强的刮削涂覆作用;TiN涂层与基体之间相互渗透形成冶金结合.     

钛-铜基阳极表面电势分布及其电化学性能

：提出利用钛-铜层状复合材料替代传统钛电极单一钛基体,对比研究其涂层电极与传统钛涂层电极的性能差异,分析了电极的表面电势分布和线性扫描伏安（LSV）曲线。结果表明：钛-铜基涂层电极对基体材料的改进,提高了电极的导电性,有利于均化电极表面电势分布和电流分布,提高了极板的电催化活性,同时具有优良的高电流密度反应稳定性。应用于电解工业时,钛-铜基涂层电极能有效地降低槽电压,提高工作电流密度,从而提高电流效率和时效产率。     

钛基Ni-Co-P非晶合金镀层电极的析氢性能

通过电沉积在钛基体上制备了非晶态Ni-Co-P合金镀层.在7mol/L NaOH溶液中进行的电化学测试结果表明,Ni-Co-P合金电极的析氢过电位明显低于镀镍阴极和纯钛阴极;计算了电极析氢反应的电化学动力学参数,表明非晶态Ni-Co-P合金电极具有较好的析氢电催化活性.     

微合金化对厚断面高锰钢铸件中夹杂物形成的影响

利用钒、钛对高锰钢进行徼合金化,研究钒、钛对厚断面高锰钢铸件中MnS夹杂物形成与分布的影响.结果表明:添加0.02%～0.1%钛和0.04%～0.1%钒能显著地细化高锰钢铸件中Mns夹杂物,并使之弥散分布.同时对高锰钢铸件中MnS 杂的形成机制进行了研究,发现加入Ti,V与N反应形成高熔点的(Ti,V)N相,凝固过程中,先析出的(Ti,V)N相质点,成为后析出MnS的异质形核质点,使MnS得到细化,弥散分布,从而提高了铸件的力学性能.     

Martensitic transformation behavior of Ti–Ni–Ag alloys

Microstructures and martensitic transformation behavior of Ti–Ni–Ag alloys prepared by arc melting were investigated by means of scanning electron microscopy (SEM), electron probe micro analysis (EPMA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and thermal cycling tests under constant load. Ti–Ni–Ag alloys consisted of Ti–Ni–Ag matrices, Ti₂Ni and TiAg phases. Ti–Ni–Ag matrices contained 0.27–0.52 at.% of solute Ag atoms depending on alloy compositions. The B2–B19′ transformation occurred in Ti–50.1Ni–0.7Ag, Ti–49.2Ni–0.9Ag, Ti–49.2Ni–0.6Ag and Ti–49.0Ni–0.7Ag alloys, while the B2-R-B19′ transformation did in Ti–47.5Ni–1.3Ag and Ti–44.4Ni–1.1Ag alloys. Thermo-mechanical treatment separated the B2-R from the R–B19′ transformation clearly and improved shape recovery by increasing the critical stress for slip deformation in a Ti–50.0Ni–0.7Ag alloy.     

The role of Fe and Ti additions in the microstructure of Nb–18Si–5Sn silicide-based alloys

The effects of Fe and Ti on the microstructure and hardness of the as cast and heat treated Nb–24Ti–18Si–5Fe–5Sn (NV8) and Nb–45Ti–15Si–5Fe–5Sn (NV4) alloys were studied. The microstructure of NV8-AC consisted of (Nb,Ti)_ss, (Nb,Ti)₃Sn, (Nb,Ti)₅Si₃, (Nb,Ti)₃Si, FeNb₄Si, and Fe₂Nb₃ and a Ti rich oxide. The microstructure of NV8-HT consisted of (Nb,Ti)₃Si, (Nb,Ti)₃Sn and the Ti rich oxide. In NV8 the formation of Nb₅Si₃ was destabilised, the stability of Nb₃Si was enhanced and the eutectic between Nb₅Si₃ and the solid solution was suppressed. The microstructure of NV4-AC contained Ti rich and Nb rich solid solutions, 3-1 and 5-3 silicides. The FeNb₄Si and Fe₂Nb₃ phases and the Ti rich oxide observed in NV8-AC were not formed in NV4-AC. The microstructure of NV4-HT consisted of (Ti,Nb)₃Sn, β(Ti,Nb)_ss, (Ti,Nb)₃Si and (Ti,Nb)₅Si₃ phases. The solubility of Fe in the Ti-based 3-1 silicide was significantly lower than in the Nb-based 3-1 silicide. The β(Ti,Nb)_ss + (Ti,Nb)₅Si₃ → (Ti,Nb)₃Si transformation was enhanced in NV4. The effects of Fe and Ti on the hardness of Nb–18Si–5Sn-based alloys, and of alloying elements on the hardness of Nb₃Sn, Ti₃Sn, and Nb₃Si, Ti₃Si, and Ti and Nb base 5-3 silicides are discussed.     

Effect of tin addition on Nb–Si-based in situ composites. Part I: Structural modifications

This paper reports the effect of adding 2 to 8 at.%Sn on the microstructure of Nb–25Ti–8Hf–2Cr–2Al–16Si. The samples were synthesised by casting and were heat treated for 5 days at 1200 °C. The as-cast and heat-treated microstructures were characterised using X-ray diffraction, scanning electron microscopy and microprobe analysis. The results revealed strong microstructural changes when Sn content exceeded 2 at.% Sn. The two-phase (Nb,Ti)_SS/γ-M₅Si₃ composite evolves towards a quaternary phase equilibrium: (Nb,Ti)_SS saturated with Sn/α-M₅Si₃/(Nb_1−xTi_x)₃(Sn_1−yTi_y)/γ′-M₅Si₃. The γ′-M₅Si₃ differs from the γ-M₅Si₃ through its Hf and Ti contents. The (Nb,Ti)_SS fraction decreases strongly, benefitting the (Nb_1−xTi_x)₃(Sn_1−yTi_y) fraction. Therefore, adding greater than 2 at.% Sn addition may dramatically affect the mechanical properties of Nb/Nb₅Si₃ composites because the solid solution (Nb,Ti)_SS has been shown to dominate the toughness of such materials.     

Structural chemistry and phase relations in intermetallic systems Ti–{Pd,Pt}–Al

Phase relations in the ternary systems Ti–{Pd,Pt}–Al have been experimentally established for the partial isothermal sections at 950°C in the Pd/Pt-poor region (<25 at.% Pd/Pt). The investigation is based on X-ray powder diffraction, metallography, SEM and EMPA techniques on about 45 alloys, which were prepared by various methods employing arc melting, levitation melting under argon or by powder reaction sintering in closed crucibles. Three ternary compounds were observed at 950°C in the Ti–Pd–Al system: τ₃-(Ti,Pd)(Ti,Pd,Al)₂ with Laves-MgZn₂-type, τ₂-(Ti,Al)₆(Ti,Pd,Al)₂₃₊₁ with a filled Th₆Mn₂₃₊₁-type and τ₁-(Ti,Pd,Al)(Ti,Pd,Al)₃ with AuCu₃-type. Due to the wide extension of the Laves phase field, there is no compatibility among γTiAl and τ₂-(Ti,Al)₆(Ti,Pd,Al)₂₃₊₁. The Ti–Pt–Al system at 950°C contains three ternary compounds: τ₃-(Ti,Al)(Ti,Pt,Al)₂ with Laves-MgZn₂-type, τ₂-(Ti,Al)₆(Ti,Pt,Al)₂₃₊₁ with the filled Th₆Mn₂₃₊₁-type and τ₁-(Ti,Pt,Al) with Cu-type. Compatibility exists for Al-rich γTiAl and τ₂-(Ti,Al)₆(Ti,Pt,Al)₂₃₊₁. The typical feature for both alloy systems studied is the three-phase equilibrium: ₂Ti₃Al+γTiAl+τ₃-(Ti,Pd/Al)(Ti,Pd/Pt,Al)₂. The solid solubility of palladium and platinum in the binary titanium aluminides, as observed from EMPA and X-ray data, is rather small and at 950°C accounts to about 2.5 at.% Pd and 2.0 at.% Pt. Two new oxide compounds Ti₃PdAl₂O_x and Ti₃PtAl₂O_x with a filled Ti₂Ni-type are observed in both quaternary systems.     

The solidification path related columnar-to-equiaxed transition in Ti–Al alloys

Columnar-to-Equiaxed Transition (CET) of binary Ti–Al alloys and multi-component Ti–48Al–2Cr–2Nb alloys is studied using Bridgman solidification technique. The effect of aluminum concentration and growth rate on CET is determined. It is found in Ti–46Al and Ti–50Al alloy ingots equiaxed grains develop ahead of the moving solid–liquid interface with a growth rate of 500 μm/s; microstructures in Ti–49Al alloy stay columnar dendrites with the same growth rate. CET in Ti–Al alloys are not only influenced by growth rate, but also by the solidification path that is related to alloying composition. CET in Ti–Al alloys is predicted using the dendritic growth model based on the criterion of growth at marginal stability. According to the calculated results and directionally solidified microstructures, values of the nucleation undercooling for α and β phases are given. The growth rates to avoid CET in Ti–48Al–2Cr–2Nb alloy are suggested.     

Composition and processing effects on the electrochemical characteristics of biomedical titanium alloys

The electrochemical behaviour of the Ti–13Nb–13Zr and Ti–6Al–4V ELI alloys with martensitic microstructures was investigated by polarization and electrochemical impedance spectroscopy (EIS) in Ringer’s solution. The impedance spectra were interpreted by a two time-constants equivalent circuit. Both investigated alloys showed high corrosion resistance, but the thin and uniform passive film on the Ti–6Al–4V ELI alloy surface was more protective. The inner barrier and outer porous layer were highly resistant and capacitive. However, thicker and more porous passive film on the Ti–13Nb–13Zr alloy surface may be beneficial for osteointegration. The suitable thermomechanical processing improved the corrosion resistance of Ti–13Nb–13Zr alloy.     

The role of Sn and Ti additions in the microstructure of Nb–18Si base alloys

The effects of Sn and Ti on the microstructure and hardness of the as cast and heat treated Nb–18Si–5Sn (NV9) and Nb–24Ti–18Si–5Sn (NV6) alloys were studied. In both alloys the phases present in the as cast and heat treated microstructures were Nb_ss, Nb₃Sn and Nb₅Si_3. In NV9, Sn suppressed the formation of Nb₃Si, partitioned in Nb_ss stronger than in Nb₅Si₃ and did not affect significantly the solubility of Si in the Nb_ss. In NV6, the solubility of Ti in (Nb,Ti)_ss increased in the presence of Sn, the concentration of Ti in Nb₅Si₃ was sensitive to cooling rate and the solubility of Sn in Nb₅Si₃ decreased as the concentration of Ti increased. The Ti controlled the partitioning of Si between (Nb,Ti)_ss and Nb₃Sn and was considered responsible for the macrosegregation of Si in the as cast ingot. The transformation of β to Nb₅Si₃ was enhanced by the synergy of Sn and Ti. The addition of Ti did not destabilise the Nb₃Sn. Silicon increased the hardness of Nb₃Sn significantly, Sn did not affect the hardness of Nb₅Si₃ and Ti reduced the hardness of Nb₃Sn and Nb₅Si₃ significantly. The hardness of NV9 and NV6 decreased and increased, respectively, by heat treatment. The reduction of the hardness of NV6-AC compared to NV9-AC is attributed to the strong effect of Ti on the hardness of Nb₃Sn and Nb₅Si₃.     

Compositional effects of Zr-rich multi-component brazing alloys on the corrosion of Zr alloy joints

High-temperature corrosion of Zircaloy-4 joints brazed by various Zr(Ti)–Cu–Ni-based multi-component alloys was studied to draw up the compositional guideline of the brazing alloy. From the compositional and microstructural effects of the joints on the corrosion, there was strong evidence for galvanic corrosion susceptibility of primary α-Zr grains (usually Sn-containing) owing to alloying of nobler Ti and its concentration gradient in a joint, inducing a microgalvanic corrosion. The Ti concentration for corrosion inhibition was proposed to be less than about 1.0 at.%. The results clearly demonstrate that the exclusion of Ti is needed for the use of Zr-rich multi-component brazing alloys.     

Effects of non-metallic inclusions on the initiation of pitting corrosion in 11% Cr ferritic stainless steel examined by micro-droplet cell

This paper explores the effects of non-metallic inclusions (NMIs) on the initiation of pitting corrosion in type 409L stainless steels refined by the argon oxygen decarburization (AOD) and vacuum oxygen decarburization (VOD) processes. The dominant NMIs in the AOD and VOD samples were (Ti, Ca)-oxides and Ti-nitrides, respectively. In-situ electrochemical noise (EN) and micro-electrochemical analyses were conducted to investigate quantitatively the inherent effects of the NMIs on the pitting corrosion of the alloys. Pitting corrosion was initiated mostly around the (Ti, Ca)-oxides in the AOD samples, while little such corrosion occurred around the Ti-nitrides in the VOD samples. In addition, the pitting resistance of the AOD samples increased with increasing Ti content and decreasing Ca content in the (Ti, Ca)-oxides.     

Ni- and Cu-free Ti-based metallic glasses with potential biomedical application

In the present work Ti–Fe–Si and Ti–Fe–Si–X (X = Zr, Pd, Ge) glassy alloys are discussed as potential biomedical materials. Depending on composition and experimental conditions these alloys possess glassy, quasicrystalline or crystalline structure. The glassy state and crystallization behavior of the melt spun ribbons were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and the Hank's solution was used as simulated body fluid for corrosion tests. Ternary Ti–Fe–Si alloys near the Ti₆₅Fe₃₀Si₅ eutectic point were prone to form quasicrystals if the cooling rate was not high enough to retain amorphous structure. The compositions on the steeper side of the eutectic point could be vitrified. The results indicate that small additions of Zr can have a positive effect on glass formation, while additions of Ge, Pd may have a detrimental effect by promoting crystallization. Ti–Fe–Si and Ti–Fe–Si–Zr alloys exhibited high corrosion properties, superior to that of pure Ti and most of Ti-based glassy alloys reported in the literature. Being free of Ni and Cu this group of alloys may be considered for possible biomedical application.