退火及置换元素对Fe-Cr-Al基合金阻尼性能及强度的影响

制备了Fe-13Cr-6Al（原子分数,%）及用2%的Mo、Mn和Nb分别置换Fe-13Cr-6Al中的Cr,用0.5%和1%的Cu分别置换Fe-13Cr-6Al中的Al共6种合金.测试了各合金的阻尼性能和强度,通过金相观察和内应力分析研究了退火温度、冷却方式及合金元素对这两种性能的影响.结果表明：随着退火温度的升高,Fe-Cr-Al基阻尼合金阻尼性能升高,强度降低;随炉缓冷合金的阻尼性能高于水淬合金的阻尼性能,而前者的强度低于后者;0.5%Cu置换Al降低了位错与溶质原子之间的交互作用,但是提高了合金原子与基体原子的弹性交互作用,使合金的阻尼性能和强度都得到了提高.     

合金元素对铸造Fe-Cr铁素体不锈钢耐浓硫酸腐蚀性能的影响

采用电化学技术、浸泡腐蚀及能谱分析等研究了合金元素对铸造Fe-Cr铁素体不锈钢耐浓硫酸腐蚀行为的影响。结果表明:随铬含量的增加,Fe-Cr合金的耐浓硫酸腐蚀性能增强,单一的铬合金化不能使Fe-Cr合金在60℃,98%H2SO4中自钝化;钼能促进Fe-Cr25-Mo合金的钝化和自钝化,随钼含量的增加,Fe-Cr25-Mo合金的耐浓硫酸腐蚀性能增强;辅助合金元素镍、铜可促进Fe-Cr25Mo2合金的钝化和自钝化,而钛、铌的影响不大。     

Effects of the Zr and Mo contents on the electrochemical corrosion behavior of Ti–22Nb alloy

Ti–22Nb–xZr and Ti–22Nb–xMo (x = 0, 2, 4, 6, in atom percent) were prepared by an arc melting method. The alloys were solution‐treated at 1073 K for 1.8 ks followed by quenching them into ice water, and the electrochemical corrosion behavior in a 0.9% NaCl solution at 25 °C and neutral pH range of the solution‐treated alloys was evaluated by using electrochemical impedance spectroscopy, polarization curves and an equivalent circuit analysis. It was found that the microstructure of the solution‐treated Ti–22Nb alloy mainly contains β phase with small amount of α″ phase, and the addition of Zr or Mo to a Ti–22Nb alloy is efficient to stabilize the β phase. The resulting impedance parameters and passive current densities indicated that the corrosion resistance of the Ti–22Nb alloy was promoted significantly with the addition of Zr and Mo.     

含氮Fe-Mn合金的阻尼性能和抗腐蚀性能

通过内耗检测技术研究了氮对Fe-14．1Mn和Fe-16．5Mn合金阻尼性能及对Fe-Mn系合金相组成和抗腐蚀性能的影响。结果表明：Fe-14．1Mn比Fe-16．5Mn合金具有更高的阻尼性能;合金中加入质量分数为0．2%的氮,两种合金的阻尼性能略有改变,合金在固溶处理时,发生了γ-ε转变,转变生成的马氏体越多,合金的阻尼性能越好;并且含氮合金在1mol/L硫酸水溶液中的抗腐蚀性能提高2倍。     

Study for corrosion characteristics of ferritic stainless steel weld metal with respect to added contents of Ti and Nb

This paper identified the effects of Ti and Nb on pitting and intergranular corrosion resistance in a ferritic stainless steel weld metal of the automobile exhaust system. We fabricated 4 flux cored wires designed with 0–0.2 wt% Ti and 0–1.0 wt% Nb and performed Flux Cored Arc Welding. Through the potentiodynamic polarization test in 0.5M NaCl, we evaluated pitting resistance. And in order to evaluate the intergranular corrosion resistance, we observed microstructure after we performed DL-EPR test in 0.5M H₂SO₄+0.01M KSCN. As a result of the test, the specimen added with 0.2%Ti+1.0%Nb showed the highest pitting resistance. From observing the degree of sensitization and microstructure, the intergranular corrosion resistance was higher as the contents of Ti and Nb increased. And through EBSD we observed Cr carbide which affects the corrosion resistance.     

Corrosion behavior of Ti‐xNb‐13Zr alloys in Ringer's solution

Ti‐6Al‐4V alloy has been widely used in restorative surgery due to its high corrosion resistance and biocompatibility. Nevertheless, some studies showed that V and Al release in the organism might induce cytotoxic effects and neurological disorders, which led to the development of V‐free alloys and both V‐ and Al‐free alloys containing Nb, Zr, Ta, or Mo. Among these alloys, Ti‐13Nb‐13Zr alloy is promising due to its better biomechanical compatibility than Ti‐6Al‐4V. In this work, the corrosion behavior of Ti, Ti‐6Al‐4V, and Ti‐xNb‐13Zr alloys (x = 5, 13, and 20) was evaluated in Ringer's solution (pH 7.5) at 37 °C through open‐circuit potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. Spontaneous passivity was observed for all materials in this medium. Low corrosion current densities (in the order of 10^?7 A/cm²) and high impedance values (in the order of 10⁵ Ωcm² at low frequencies) indicated their high corrosion resistance. EIS results showed that the passivating films were constituted of an outer porous layer (very low resistance) and an inner compact layer (high resistance), the latter providing the corrosion resistance of the materials. There was evidence that the Ti‐xNb‐13Zr alloys were more corrosion resistant than both Ti and Ti‐6Al‐4V in Ringer's solution.     

合金元素对新型Co-Al-W合金热腐蚀行为的影响

研究了由γ'-Co₃(Al,W)相沉淀强化的新型钴基Co-Al-W 高温合金在800℃、75% Na₂SO₄+25% NaCl熔盐中的热腐蚀动力学及合金元素Mo、Nb、Ta和Ti对合金热腐蚀行为的影响。研究发现,2Mo、2Nb、 2Ta和2Ti合金比9.8W合金具有更好的抗热腐蚀能力,Mo和Ti对提高合金耐热腐蚀能力的效果比Ta和Nb显著。加入合金元素的合金热腐蚀膜由三层组成,即主要由Co氧化物CoO和Co₃O₄组成的腐蚀膜外层,由合金元素、Al、 Co及W复杂氧化物组成的中间过渡层和由Al、Co氧化物组成的腐蚀膜内层。随着腐蚀时间的增加,中间过渡层厚度逐渐增加,热腐蚀膜内、外层厚度变化不大,但内层致密性逐渐增加。     

合金化元素Ti对Laves相Cr_2Nb力学性能及耐蚀性的影响

采用真空非自耗电弧熔炼工艺制备了Cr2Nb-XTi(X=5,10,15,at%)合金,利用光学显微镜(OM),X射线衍射(XRD)仪,扫描电镜(SEM)对电弧熔炼态铸锭的组织进行了研究,探讨了合金化元素Ti的含量对Laves相Cr2Nb力学性能及耐蚀性的影响。结果表明:3种成分的电弧熔炼态合金凝固组织主要由C15-Cr2(Nb,Ti)相和六方的β-(Ti,Nb)以及体心立方结构的β-(Nb,Ti)相组成。在5Ti和10Ti合金冷速较小的铸锭上部凝固组织中出现了亚稳相C14-Cr2(Nb,Ti)。通过对合金力学性能研究表明,随合金化元素Ti含量的增加,Laves相Cr2Nb合金的显微硬度逐渐降低,断裂韧性增大,当Ti含量达到15at%时,合金的断裂韧性达到了3.1 MPa·m1/2,比单相Laves相Cr2Nb提高1倍。另外,对腐蚀性能的测试表明,Ti含量增加材料腐蚀性能下降,但15Ti合金仍表现出良好的耐蚀性。     

Relationship between phase composition and corrosion resistanceof Ni-Ti-Nb based shape memory alloys

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合金元素对Ti_3Al基金属间化合物热腐蚀性能的影响

采用表面涂盐法研究了Nb、Mo、V、Si等合金元素对Ti_3Al金属间化合物于900—950t空气中的热腐蚀性能的影响.结果表明,Ti_3Al基金属间化合物均遭受热腐蚀,其腐蚀进程可用电化学机理模型加以描述.Nb可以通过促进富AI氧化物层的形成而显著提高Ti;Al耐热腐蚀性能.在此基础上添加Si则可以使其耐热腐蚀性能得到进一步提高,并且随Si含量的增加,合金的耐蚀性能越好;但如果加入M。、V则会使其耐热腐蚀明显变差.但本实验中Nb、Si等合金元素的添加仍不足以使Ti3Al合金表面形成单一的Al2O3阻挡层     

Effect of alloying elements on the behaviour of TiAl-based alloys

TiAl-based alloys containing Nb, Mo and Cr have been produced by induction melting both under an Ar atmosphere and in vacuum. Fracture toughness and isothermal oxidation tests at 900 °C have been performed on a number of alloys in order to evaluate the effect of alloying elements on both fracture toughness and hot corrosion. The results highlighted that there is an alloy composition range that could allow to obtain a good compromise between high temperature oxidation resistance and fracture toughness. In fact only for a selected Al/Ti ratio and a limited content of alloying elements it is possible to attain the alloy microstructural control and, for Mo free alloys, good protectiveness against oxidation.     

Untersuchungen über das Korrosionsverhalten von Zirkoniumlegierungen. III. Untersuchungen an Zirkonium-Titan-Legierungen

Investigations into the corrosion behaviour of zirconium alloys III. Investigations on zirconium titanium alloys Investigations on zirconium alloys containing up to 4OO% titanium and, eventually, up to 10% Nb or Mo and small amounts of Fe, Ni and Cr (together 1.5% maximum) have revealed that titanium increases the dissolution power of zirconium for other alloying elements without tending to form two-phase structures. As to corrosion behaviour the better alloys are somewhat superior to other alloys. While titanium impairs the corrosion resistance of pure zirconium with respect to boiling mineral acids (20% HCl, sulphuric or nitric acids) titanium additions up to 10% of improve the corrosion behaviour of ZrNb and ZrMo alloys; alloys of the type Zr10Nb10Ti or Zr10Ti10Ta are comparable, with respect to the corrosion resistance, to pure zirconium. The scaling resistance of zirconium passes through a minimum at a five to ten percent Ti and arrives at its maximum value with 40% Ti. Further improvements may be obtained by addition of 10% Nb.     

钛对铁锰基减振合金阻尼性能和耐蚀性能的影响

采用内耗检测技术研究了Ti对Fe-14Mn、Fe-17Mn和Fe-23Mn合金阻尼性能的影响,研究了Ti对Fe-Mn系合金相组成和耐蚀性能的影响.结果表明,Fe-17Mn比Fe-14Mn和Fe-23Mn具有更高的阻尼性能;在Fe-Mn合金中加入质量分数为1.0％的钛,合金的阻尼性能均受到影响,合金在固溶处理时,发生了γ...     

New stainless steels for sea-water applications. Part II: Comparison of corrosion and mechanical properties of laboratory and commercial ELI ferritic and superaustenitic stainless steels

This paper represents a follow-up to the first part of the work on new stainless steels for sea-water service. Four laboratory ELI (Extra Low Interstitial) ferritic stainless steels (types 25 Cr-4 Ni-4 Mo), two commercial ELI ferritic stainless steels (types 25 Cr-4 Ni-4 Mo? Ti and 26 Cr-2.5 Ni-3 Mo? Ti) and two highly alloyed austenitic stainless steels (types 20 Cr-25 Ni-4.5 Mo? Cu and 20 Cr-18 Ni-6 Mo? N) have been investigated. With a view to establish the performance of these new alloys in chloride containing environments, systematic electrochemical and laboratory exposure tests have been carried out to define how various factors affect its susceptibility to intergranular, pitting, crevice and stress corrosion. Tension tests were also performed. From the comparison of the localized corrosion resistance and mechanical properties it has been concluded that the laboratory Ti, Ti + Nb or Nb stabilized ELI ferritic stainless steels and the commercial type 25 Cr-4 Ni-4 Mo? Ti of analogous composition could be a valuable alternative to the more expensive highly alloyed stainless steel type 20 Cr-25 Ni-4.5 Mo? Cu which has been especially developed and already used for industrial sea-water applications.     

Shape memory properties of Ti–Nb–Mo biomedical alloys

Mo is added to Ti–Nb alloys in order to enhance their superelasticity. The shape memory properties of Ti–(12–28)Nb–(0–4)Mo alloys are investigated in this paper. The Ti–27Nb, Ti–24Nb–1Mo, Ti–21Nb–2Mo and Ti–18Nb–3Mo alloys exhibit the most stable superelasticity with a narrow stress hysteresis among Ti–Nb–Mo alloys with Mo contents of 0, 1, 2 and 3 at.%, respectively. The ternary alloys reveal better superelasticity due to a higher critical stress for slip deformation and a larger transformation strain. A Ti–15Nb–4Mo alloy heat-treated at 973 K undergoes (2 1 1)〈1 1 1〉-type twinning during tensile testing. Twinning is suppressed in the alloy heat-treated at 923 K due to the precipitation of the α phase, allowing the alloy to deform via a martensitic transformation process. The Ti–15Nb–4Mo alloy exhibits stable superelasticity with a critical stress for slip deformation of 582 MPa and a total recovery strain of 3.5%.     

Sulfidation properties of TiAl–2 at.% X (X=V,Fe, Co,Cu, Nb,Mo, Ag and W) alloys at 1173 K and 1.3 Pa sulfur pressure in an H2S–H2 gas mixture

TiAl–2 at. % X (X=V, Fe, Co, Cu, Nb, Mo, Ag and W) alloys were sulfidized at 1173 K for 86.4 ks at a 1.3 Pa sulfur pressure in an H₂–H₂S gas mixture. The structure, phases, and compositions of the external sulfide scale and alloy surface layer were measured using EPMA and X-RD. The TiAl–2Ag and –2Cu alloys sulfidized faster than TiAl, and the alloy surface layer was thicker than that of TiAl. Sulfidation amounts of the TiAl–2X (X=V, Co, Fe, Mo, W and Nb) alloys were almost the same as that of TiAl, while the thickness of the alloy surface layer decreased in the order: V>Co>Fe>Mo>[Cr (by Narita T, Izumu T, Yatagai M, Yoshioka T. Intermetallics, 2000;8:371)]>W>Nb. The sulfide scale was composed of multi-layer structures: an outermost (rich in Ti-sulfides), an outer (rich in Al₂S₃), an inner (a mixture of Ti-sulfides and Al₂S₃), and an innermost (rich in Ti-sulfides) layer. The alloy surface layer also had a multi-layer structure, and was classified into four groups: group 1 for TiAl–2V and –2Co alloys as well as TiAl binary alloy where the surface layer consists of alloy substrate/TiAl₂/TiAl₃/sulfide scale, group 2 for TiAl–2Nb, –2Mo, and –2W (and also– 2Cr) alloys with alloy substrate/TiAl₂/TiAl₃/(Nb, Mo, W or Cr)–Al alloy/sulfide scale, group 3 for TiAl–2Cu and –2Ag alloys with alloy substrate/TiAl₂/Ti (Al, Ag or Cu)₃ with an L1₂ structure/TiAl₃/sulfide scale, and group 4 for TiAl–2Fe alloy with alloy substrate/TiAl₂/Ti(Al,Fe)₃ with an L1₂ structure/TiAl₃/FeAl₃/sulfide scale. Diffusion paths for these four groups were shown in a tentative Ti–Al–X ternary phase diagram.     

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.     

Electrochemical behavior of TiN film coated Ti−Nb alloys for dental materials

In order to study the electrochemical behaviors of TiN film coated Ti−Nb alloys for dental materials, Ti containing Nb up to 3, 20, and 40 wt.% was melted by a vacuum furnace and coated with TiN by EB-PVD. the electrochemical behaviors were investigated using a potentiostat in 0.9% NaCl solution and the corrosion surface was observed using SEM and XPS. Ti−3Nb and Ti−20Nb alloys have α+β phase structure. In the case of Ti−40Nb, the microstructure had a coarse β phase. The microstructural changed from equiaxed to acicular and an increase of β-phase in Ti−Nb alloys was observed with increased Nb content. The current density at 300 mV (potential of oral environment) of Ti−40Nb alloy was lower than that of the other alloys in 0.9% NaCl. The pitting corrosion resistance of Ti−40Nb was higher than that of Ti−3Nb and Ti−20Nb alloys in the 0.9% NaCl solution. The corrosion potential and pitting potential of TiN coated Ti alloy increased with increasing Nb content but the current density at 300 mV and the current density at the passive region decreased. The TiN coated Ti−40Nb alloy offers good corrosion resistance for dental implants compared with non-TiN coats alloys.     

Corrosion resistant Ti alloy for sulphuric acid medium: Suitability of Ti–Mo alloys

The corrosion resistance of Ti–Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5–25% sulphuric acid was evaluated. The Ti–Mo alloys offered a better corrosion resistance than commercially pure titanium (CP‐Ti). The higher impedance values, higher phase angle maximum, ability to reach the phase angle maximum at relatively lower frequencies, ability to exhibit a constant phase angle maximum over a wider range of frequencies, higher phase angle values at 0.01 Hz, have confirmed the formation of a stable passive oxide film on Ti–Mo alloys. The study recommends the use of Ti–Mo alloys, particularly Ti–25Mo alloy, as a suitable material of construction for sulphuric acid medium.     

Microstructure and properties of novel quinary multi-principal element alloys with refractory elements

Five equiatomic alloys(Ti Zr Hf VNb, Ti Zr Hf VTa, Ti Zr Nb Mo V, Ti Zr Hf Mo V and Zr Nb Mo Hf V) composed of five elements with high melting temperature, respectively were prepared by arc-melting to develop a novel high temperature alloy. The five alloys exhibit different dendritic and interdendritic morphologies. The Ti Zr Hf VNb, Ti Zr Hf VTa and Ti Zr Nb Mo V alloys formed disordered solid solution phases with body-centered cubic structure, and exhibited high compressive strength and good plasticity. The Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys are composed with Laves phase(Hf Mo2) and disordered solid solution phases with body-centered cubic structure. The Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys are harder and more brittle than the other three alloys due to the existence of hard and brittle Laves phases. At high temperatures, the strength decreases to below 300 MPa for the Ti Zr Hf VNb and Ti Zr Hf Mo V alloys. Solution strengthening is the primary strengthening mechanism of the Ti Zr Hf VNb, Ti Zr Hf VTa and Ti Zr Nb Mo V alloys, and brittle Laves phase is the main cause for the low ductility of the Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys.