纳米晶Cu-20Ag-20Cr合金在H2SO4溶液中的腐蚀电化学行为

利用机械合金化法通过控制球磨时间分别制备出粗晶和纳米晶Cu-20Ag-20Cr合金粉末,采用真空热压法分别制备了粗晶和纳米晶Cu-20Ag-20Cr块体合金.使用PAR273与M5210电化学综合测试仪通过测定两种Cu-20Ag-20Cr合金在不同浓度H2SO4溶液中动电位极化曲线和交流阻抗谱(EIS)等研究了晶粒细化对其腐蚀电化学行为的影响,发现随着H2SO4溶液浓度的增大,粗晶和纳米晶Cu-20Ag-20Cr合金的自腐蚀电位负移;向中性Na2SO4溶液中加入0.02 mol/L H2SO4,腐蚀电流密度明显增大,但随着H2 SO4溶液浓度的增大,腐蚀电流密度变化不大.晶粒细化后,Cu-20Ag-20Cr块体合金的腐蚀电流密度变大,活性溶解增强,腐蚀速度加快;当H2SO4的浓度为0.50 mol/L时,两种Cu-20Ag-20Cr合金均发生了钝化,纳米晶Cu-20Ag-20Cr合金表面形成钝化膜时的维钝电流密度明显小于粗晶Cu-20Ag-20Cr合金,表明晶粒细化后,合金的钝化性能得到改善,稳定性增强;在H2SO4溶液中,两种Cu-20Ag-20Cr合金的交流阻抗谱均在高频处呈连续的圆弧,在低频端出现了“扩散尾”,在中性Na2SO4溶液中容抗弧的曲率半径最大,加入H2SO4溶液后,容抗弧的曲率半径显著变小,随着H2SO4溶液浓度的增大,容抗弧曲率半径的大小变化不大.     

纳米晶镍脉冲电沉积层在NaCl和NaOH溶液中的腐蚀性能

目前,对纳米材料耐腐蚀性研究的结论不尽相同,对其腐蚀机制的见解也不统一.通过脉冲电沉积方法制备了纳米晶Ni沉积层.采用浸泡法和电化学方法研究了纳米晶Ni沉积层在3.5%NaCl(质量分数)以及10.0%NaOH(质量分数)溶液中的腐蚀行为.结果表明:在3.5%NaCl溶液中,纳米晶Ni沉积层具有较低的自腐蚀电位和较宽的钝化区,其耐腐蚀性能随着晶粒尺寸的减小而降低;在10.0%NaOH溶液中,纳米晶Ni沉积层的阳极极化曲线有较宽的钝化区,其耐腐蚀性能随着晶粒尺寸的减小而提高.     

合金元素对块体纳米晶Fe3Al材料磁学性能的影响

为了研究合金元素对块体纳米晶Fe3Al材料磁学性能的影响,通过铝热反应熔化法制备了纳米晶Fe3Al以及分别含Ni质量分数10%、Cr质量分数10%、Mn质量分数10%和含Ni质量分数10%-Cu质量分数2%的块体纳米晶Fe3Al.在振动样品磁强计(VSM)上测得合金的磁滞回线,分析其磁性能,采用X射线衍射仪进行结构分析和平均晶粒尺寸计算.结果表明:各样品的磁滞回线呈倾斜状且狭长,磁滞损耗很小;含Ni质量分数10%的样品饱和磁化强度Ms较大,剩余磁化强度Mr和矫顽力Hc较其他样品最小,具有较好的软磁性能;添加合金元素后几种材料的晶粒尺寸变小,磁性能有较大变化,合金元素对纳米晶Fe3Al块体材料的磁性能影响明显.     

高压下Fe73.5Cu1Nb3Si13.5B9纳米晶软磁块体合金的形成

采用MA法和低温高压固结工艺制备了Fe73.5Cu1Nb3Si13.5B9软磁合金粉末和块体合金, 借助XRD、DSC、SEM、TEM手段分析了它们的相组成、平均晶粒尺寸以及粉末的热稳定性、块体合金的相对密度.结果表明 (1)经过70h MA后, 可获得平均晶粒尺寸约9.5nm、bcc结构的单相α-Fe纳米晶过饱和固溶体粉末; (2)在DSC的升温曲线中, 分别出现四个强弱不一的放热峰, 依次对应着发生了畸变的纳米晶过饱和固溶体的结构弛豫过程、少量非晶晶化过程以及过饱和固溶体的相析出过程, 且过饱和固溶体析出过程分两个阶段完成; (3)在P=5.5GPa, Pw=980W, t=5min的烧结条件下, 可获得相对密度约98.4%、平均晶粒尺寸约12.5nm的单相α-Fe纳米晶块体合金, 该块体合金的软磁性能为 比饱和磁化强度Ms=1.71×10-7Wb·m/g, 矫顽力Hc=8.22×103A/m.     

铜模吸铸法制备的Fe74Al4Sn2P10Si4B4C2块体非晶与块体纳米晶合金

利用铜模吸铸法制备了直径φ1.0mm和2.0mm的Fe74Al4Sn2P10Si4B4C2块体非晶合金和直径2.0mm的Fe74Al4Sn2P10Si4B4C2块体纳米晶合金圆棒.利用X射线衍射、差示扫描量热仪(DSC)和差热分析仪(DTA)对Fe74Al4Sn2P10Si4B4C2块体非晶合金的结构和热性质进行了测定.该非晶合金的超冷液相区△Tx为16.7K,约化玻璃转变温度Tg/Tm和Tg/T1分别为0.60和0.57.Fe74Al4Sn2P10Si4B4C2合金接近共晶成分,在10K/min的冷却速率下其过冷度可达86.7K.利用透射电子显微镜(TEM)观察了制备态的Fe74Al4Sn2P10Si4B4C2纳米晶合金圆棒的结构,为非晶基体上均匀分布的尺寸10～20nm的α-Fe晶粒.Fe74Al4Sn2P10Si4B4C2合金能达到较大的过冷度,具有较高的约化玻璃转变温度(接近共晶合金成分)和过冷合金熔体的二步相析出有利于块体非晶合金和块体纳米晶合金的形成.铜模吸铸法既可制备块体非晶合金,也可制备块体纳米晶合金,是一种很有吸引力的制备块体非晶合金和块体纳米晶合金的方法,并进一步证实利用快速凝固法可以直接制备块体纳米晶合金.     

Ni,Mo和Cu添加对13Cr不锈钢组织和抗CO2腐蚀性能的影响

采用正交实验法,通过等离子电弧炉制备添加不同含量Ni,Mo和Cu元素的13Cr不锈钢,研究合金的微观组织、结构特征以及饱和CO2油田采出液中的腐蚀电化学和高温高压浸泡腐蚀行为。结果表明:合金组织主要为马氏体和铁素体,随Ni,Mo和Cu含量不同而变化;Ni4Mo1.2Cu1.4合金中马氏体含量较高,硬度达到296.48HV1.0;所有合金均呈现出明显钝化特征,Ni4Mo1.2Cu1.4合金具有最低的维钝电流密度2.99×10-6A.cm-2和最高的点蚀电位0.35V(SCE),钝化稳定性最高;制备合金在高温高压下的浸泡腐蚀速率为0.041～0.053mm/a,低于0.076mm/a;Ni,Mo和Cu元素加入提高了合金的自腐蚀电位,降低了腐蚀倾向,其中Cu对于改善合金耐蚀性能作用最为突出。     

Ti-Zr-Be-Cu块体非晶合金添加不同含量Co后在HCl溶液中的腐蚀行为

添加合金元素可提高非晶合金的耐蚀性.对Ti-Zr-Be-Cu块体非晶合金添加Co,采用电化学极化曲线和浸泡腐蚀法研究所制备的Ti35Zr30Be27.5-xCu7.5Cox(x=3.5,7.5,11.5)块体非晶合金在不同温度1 mol/L HCl溶液中的腐蚀行为,探讨添加Co元素提高Ti-Zr-Be-Cu块体非晶合金耐蚀性的机理.结果表明:Ti35Zr30Be27.5-xCu7.5Cox块体非晶合金在298 K的1 mol/L HCl溶液中都具有很好的耐蚀性,阳极极化曲线表现出明显的钝化特征,随着Co元素含量的增大其耐蚀性能逐渐增强,非晶合金的自腐蚀电位高于不锈钢,自腐蚀电流密度比不锈钢小1个数量级;在313,333 K的1 mol/L HCl中浸泡腐蚀失重,随Co含量增大,非晶合金耐蚀性增强.     

Ni,Mo和Cu添加对13Cr不锈钢组织和抗CO_2腐蚀性能的影响EI北大核心CSCD

采用正交实验法,通过等离子电弧炉制备添加不同含量Ni,Mo和Cu元素的13Cr不锈钢,研究合金的微观组织、结构特征以及饱和CO2油田采出液中的腐蚀电化学和高温高压浸泡腐蚀行为。结果表明:合金组织主要为马氏体和铁素体,随Ni,Mo和Cu含量不同而变化;Ni4Mo1.2Cu1.4合金中马氏体含量较高,硬度达到296.48HV1.0;所有合金均呈现出明显钝化特征,Ni4Mo1.2Cu1.4合金具有最低的维钝电流密度2.99×10-6A.cm-2和最高的点蚀电位0.35V(SCE),钝化稳定性最高;制备合金在高温高压下的浸泡腐蚀速率为0.041～0.053mm/a,低于0.076mm/a;Ni,Mo和Cu元素加入提高了合金的自腐蚀电位,降低了腐蚀倾向,其中Cu对于改善合金耐蚀性能作用最为突出。     

纳米复合Al-Ni-Y系铝合金的制备技术

部分晶化非晶铝合金因其优异力学性能备受关注,对块体非晶铝合金制备技术的研究意义重大.本工作通过紧耦合惰性气体雾化技术制备了Al82Ni10Y8非晶及纳米晶粉末,随后利用超高压固结成形技术对雾化粉末进行致密化.制备所得的块体材料获得了非晶及纳米晶的复合结构.利用差示扫描量热分析,X射线衍射,扫描电镜和透射电镜等测试手段对合金的热稳定性,物相组成,微观组织和形貌进行了分析,并探讨了合金的可能致密化机理.     

低温退火对电沉积纳米晶Ni镀层耐蚀性的影响

通过脉冲电沉积方法制备纳米晶Ni镀层。采用浸泡法和电化学方法研究了不同温度低温退火纳米晶Ni镀层在3.5wt.%NaCl和5wt.%HCl溶液中的腐蚀行为。结果表明:150℃以下退火,晶粒未出现明显长大。在3.5wt.%NaCl溶液中,镀层耐蚀性随退火温度的升高而提高;200℃退火后镀层的耐蚀性最好,镀层表面均有钝化现象。在5wt.%HCl溶液中,退火后镀层的耐蚀性有所提高,但退火温度的影响不大,镀层腐蚀过程中未观察到钝化现象。     

FeCrMnNiTix高熵合金在NaCl溶液中的腐蚀行为研究

将Fe,Cr,Mn,Ni和Ti 5种金属纳米粉体经行星式球磨机混合后,采用真空熔铸法制备FeCrMnNiTi,FeCrMnNiTi_0.5,FeCrMnNi 3种高熵合金。为研究这3种合金在NaCl溶液中的腐蚀行为,运用电化学工作站测定3种合金在质量分数为3.5%的NaCl溶液中的开路电位、极化曲线和交流阻抗,利用金相显微镜和扫描电镜对腐蚀后的合金进行微观组织观察。电化学测试结果表明:当FeCrMnNiTi合金的自腐蚀电位为-0.301 V时,FeCrMnNiTi_0.5合金的自腐蚀电位为-0.443 V;腐蚀产物形貌观察表明:FeCrMnNiTi_0.5以晶界腐蚀为主,另外2种合金以点蚀为主。由此得出结论:FeCrMnNiTi耐蚀性最好,FeCrMnNiTi_0.5耐蚀性最差;加入Ti可能造成了合金晶格畸变。     

In vitro corrosion and cytotoxicity on microcrystalline, nanocrystalline and amorphous NiTi alloy fabricated by high pressure torsion

Bulk nanocrystalline and amorphous Ni50.2Ti49.8 alloy samples were successfully prepared from commercial microcrystalline Ni50.2Ti49.8 alloy discs by high pressure torsion (HPT) technique. Then their corrosion resistance, surface wettability and cytotoxicity were further studied from the viewpoint of biomaterials. In both Hank's solution and artificial saliva, bulk nanocrystalline and amorphous Ni50.2Ti49.8 alloys showed significantly higher pitting corrosion potentials than that of microcrystalline Ni50.2Ti49.8 alloy. Meanwhile, the amount of Ni ion release after immersion in Hank's solution was minor, far below the threatening threshold of daily diet. Murine fibroblast and osteoblast cell lines were indirectly co-cultured with experimental sample extracts, indicating no cytotoxicity. Amongst all samples, the nanocrystalline Ni50.2Ti49.8 shows promising as best biomaterial candidate for its good combination of mechanical property, corrosion resistance and cytocompatibility.     

Electrochemical characteristics of nano and microcrystalline Fe–Cr alloys

The electrochemical behavior of nano and microcrystalline Fe–10Cr and Fe–20Cr alloys was determined using potentiodynamic polarization in 0.5 M H₂SO₄. Disks of the alloys were prepared by high-energy ball milling followed by compaction and sintering. In the current study, nanocrystalline Fe–Cr alloys reveal significantly different electrochemical characteristics, typified by lower anodic current densities and more negative passivation potentials, compared with their microcrystalline counterparts. In addition to the differences in grain boundary density, compositional characterization of corrosion films carried out by X-ray photoelectron spectroscopy indicates a higher Cr content in the film developed upon nanocrystalline Fe–Cr alloys. Mechanisms for observed enhancement in the corrosion performance of the nanocrystalline Fe–Cr alloys are discussed.     

新型铝合金阳极电化学性能与组织研究

研制了两种新型铝合金阳极材料；用恒电流方法和动电位方法测定了铝合金阳极在碱性氯化钠（25％KOH＋3．5％NaCl）介质中的电化学性能；用金相显微镜、扫描电子显微镜观察了新型铝合金的微观组织和阳级溶解后的表面腐蚀状态。结果表明：固溶于铝基体的微量合金化元素Ga、In及其适量均匀分布的第二相，可以破坏铝氧化膜的致密结构，促使铝基体的正常溶解，减少铝阳极极化，使铝合金阳极的稳定电极电位变得更负；加入能改变铝基体中杂质的存在状态和降低杂质含量的合金化元素Mg等，可以改善铝阳极的腐蚀均匀性，降低自腐蚀速度，提高阳极利用率。     

Biocompatibility and corrosion behavior of the shape memory NiTi alloy in the physiological environments simulated with body fluids for medical applications

Due to unique properties of NiTi shape memory alloys such as high corrosion resistance, biocompatibility, super elasticity and shape memory behavior, NiTi shape memory alloys are suitable materials for medical applications. Although TiO₂ passive layer in these alloys can prevent releasing of nickel to the environment, high nickel content and stability of passive layer in these alloys are very debatable subjects. In this study a NiTi shape memory alloy with nominal composition of 50.7 atom% Ni was investigated by corrosion tests. Electrochemical tests were performed in two physiological environments of Ringer solution and NaCl 0.9% solution. Results indicate that the breakdown potential of the NiTi alloy in NaCl 0.9% solution is higher than that in Ringer solution. The results of Scanning Electron Microscope (SEM) reveal that low pitting corrosion occurred in Ringer solution compared with NaCl solution at potentiostatic tests. The pH value of the solutions increases after the electrochemical tests. The existence of hydride products in the X-ray diffraction analysis confirms the decrease of the concentration of hydrogen ion in solutions. Topographical evaluations show that corrosion products are nearly same in all samples. The biocompatibility tests were performed by reaction of mouse fibroblast cells (L929). The growth and development of cells for different times were measured by numbering the cells or statistics investigations. The figures of cells for different times showed natural growth of cells. The different of the cell numbers between the test specimen and control specimen was negligible; therefore it may be concluded that the NiTi shape memory alloy is not toxic in the physiological environments simulated with body fluids.     

双稀土处理液对H62黄铜成膜耐蚀性能的影响

为了提高H62黄铜合金的表面性能,通过正交试验获得了最佳锅、钵双稀土处理液配方。利用硝酸点滴、中性盐雾试验评价了H62黄铜合金钝化膜的耐蚀性能,通过电子探针(EPMA)观测了其表面形态结构及元素分布,利用电化学方法表征了 H62黄铜表面钝化膜在3.5%NaCl溶液中的缓蚀行为,采用XRD对H62黄铜表面钝化膜的成分进行了检测。结果表明:H62黄铜合金由镉、钵双稀土处理液钝化成膜的主要成分为Cu2O,CeO2,La(OH)3,Ce(OH)4;致密的钝化膜耐硝酸点滴时间达到21.98s,在3.5%NaCl溶液自腐蚀电位增加,腐蚀电流降低,腐蚀速度明显降低,耐蚀性能增加,耐中性盐雾性能明显优于鋪单一稀土处理液。     

无铅焊料的盐雾腐蚀性能研究

无铅焊料已经进入实用化研究阶段，Sn-3Ag-0．5Cu及sn-8Zn-3Bi等几种典型合金在-些电子产品中已经得到实际应用。然而对于上述无铅焊料的腐蚀性却报道较少。选取Sn-3Ag-0．5Cu、Sn-8Zn-3Bi及Sn-8Zn-3Bi—Nd合金进行盐雾腐蚀实验，对腐蚀表面进行宏观及微观分析，并与传统的sn—Pb焊料对比，考察焊料合金的耐腐蚀性能。结果表明：Sn-3Ag-0．5Cu具有比传统Sn—Pb焊料更优越的耐腐蚀性能；Sn-8Zn。3Bi合金由于组织中存在更为粗大的初生Zn相易于优先腐蚀而导致抗盐雾腐蚀性能不良，因此在腐蚀开始阶段腐蚀速率相对Sn-8Zn-3Bi—Nd合金更快，但后者初生相数量更多，因此在更长时间腐蚀后腐蚀量更大。     

Corrosion behaviors of amorphous and nanocrystalline Fe-based alloys in NaCl solution

Amorphous Fe(73.5)Si(13.5)B9Nb3Cu1 alloy was prepared by the chill block melt-spinning process and nanocrystalline Fe(73.5)Si(13.5)B9Nb3Cu1 alloy was obtained by annealing. The crystallization behaviors were analysed by DSC, XRD and TEM. The electrochemical corrosion behaviors in different annealed states were performed by linear polarization method and electrochemical impedance spectroscopy in 3.5% NaCl solution. The results show that the crystallization of amorphous alloy occurs in the two steps. Some nanometer crystals appear when annealing in 550 degrees C and 600 degrees C, respectively with grain size 13 nm and 15 nm. The nanocrystalline alloy has a tendency to passivation and lower anodic current density than amorphous alloy. It indicates that nanocrystalline alloy has a higher corrosion resistance. Amorphous Fe(73.5)Si(13.5)B9Nb3Cu1 alloy consisted of only single semi-circle. When the alloy was annealed in 600 degrees C, its EIS consisted of two time constants, i.e., high frequency and low frequency capacitive loops. The charge transfer reaction resistances increases as annealing temperature rises.     

Mo含量对CoCrFeNiMo高熵合金组织及耐蚀性能的影响

高熵合金由于具有优异的机械性能及耐蚀性能在涂层工业领域备受关注。采用同步送粉激光熔覆技术在Q235钢表面制备了CoCrFeNiMo_x高熵合金涂层,研究了涂层的组织结构和耐蚀性能,并结合第一性原理计算分析了涂层耐蚀机理。研究结果表明：CoCrFeNiMo_0.1、CoCrFeNiMo_0.2高熵合金涂层是由fcc相组成,而CoCrFeNiMo_0.3高熵合金涂层则由fcc相和σ相组成。合金的晶粒主要呈树枝晶,枝晶间富集Cr、Mo元素,枝晶内富集Co、Fe元素。在3.5%(质量分数)NaCl溶液中,CoCrFeNiMo_x高熵合金涂层具有优良的综合耐蚀性能;并且随着Mo元素含量的增加,涂层的腐蚀电位正移,腐蚀电流密度减少,钝化区间变长,阻抗弧半径增大,电极反应阻力增强。通过第一性原理计算证明,涂层较高的耐蚀性能与表面致密的钝化膜形成密切相关。     

On the corrosion characteristics of some commercial magnetic metallic glasses in NaCl solution

The corrosion characteristics of six commercial magnetic metallic glasses, namely Fe₇₈B₁₃Si₉ (Metglas 2605-S-2), Fe₆₇Co₁₈B₁₄Si (Metglas 2605 Co), Fe₄₀Ni₄₀B₂₀ (Vitrovac 0040), Fe₃₉Ni₃₉Mo₂(SiB)₂₀ (Vitrovac 4040), Fe₄₀Ni₃₈Mo₄B₁₈ (Metglas 2826 MB) and Fe₄₀Ni₄₀P₁₄B₆ (Metglas 2826) in which iron and boron are common base elements have been studied by immersion tests and potentiostatic techniques in various concentrations of NaCl solutions at room temperature. In exposure for up to six days, weight loss observations indicated that the corrosion rates in 3.5% NaCl were in the following increasing order: 2826 < 4040 < 0040 < 2826 MB < 2605 Co < 2605-S-2. During exposure for up to four hours under open-circuit conditions, 2826 alloy showed the noblest behaviour while 2605-S-2 was the least noble. All the alloys, except 2826, showed rapid dissolution without any passivation during anodic polarization. Phosphorus addition to Fe-Ni-B glass enhanced the active dissolution and resulted in the formation of a black prepassive film in the active region (0.2V) which becomes protective in the passive region (0.3 to 1.25V). The values ofI _crit. andI _pass. (the critical and passive current densities) decreased with a decrease of concentration from 3.5 to 0.01% NaCl, while in 0.001% NaClI _pass. slightly increased and the passivation potential range decreased. The corrosion resistance of Fe-B metallic glasses increased with metal addition in the order Co < Mo < Ni and with metalloid addition in the order Si < P.