超细亚晶粒铝合金的强化机理

在室温下对经过时效处理的2024铝合金实施了等效应变为0.5的等通道转角挤压(ECAP)变形,将形变强化、时效强化和晶界细化强化有机结合,制备出超细亚晶粒铝合金,其硬度、屈服强度、伸长率分别约达100 HV,130 MPa和31%.分析探讨了超细亚晶粒2024铝合金的强化机理.研究结果表明,屈服强度的实测数值和理论计算...     

Mg-Al和Mg-Li镁合金板在NaCl水溶液中的腐蚀行为

采用电化学方法分别研究了AZ31镁合金轧制板、AZ80镁合金轧制板、ZE42镁合金热挤压板、LZ91镁合金轧制板和LA101镁合金热挤压棒等5种不同的镁合金在质量浓度为5.0%氯化钠水溶液中的腐蚀行为。采用失重法测量每一种合金的腐蚀速率,并且采用扫描电镜(SEM)观察了腐蚀产物的形貌,利用X射线衍射仪(XRD)分析了每种镁合金的相组成。结果表明:电势分布较为均匀的镁合金可减小镁合金的微电偶腐蚀趋势,5种镁合金板(棒)材在NaCl水溶液中的腐蚀速率由低到高的顺序是:AZ80AZ31LA101LZ91ZE42。经36 h浸泡腐蚀后,在NaCl水溶液中镁合金表面主要被腐蚀产物Mg(OH)_2所覆盖,且随着浸泡时间延长,所有镁合金均呈现出明显的点蚀特征,阳极溶解和局部腐蚀程度加重,发生析氢反应,最后变为均匀腐蚀。     

Microstructure,mechanical properties and wear resistance of an Al–Mg–Si alloy produced by equal channel angular pressing

Microstructure, mechanical properties and wear resistance in an ultrafine-grained Al–Mg–Si alloy fabricated utilizing a combination of equal channel angular pressing (ECAP) and dynamic aging were investigated in this paper. The results indicated that the grain size of the ECAP alloy was significantly refined, i.e., to ~239 nm after three ECAP passes. Meanwhile, the yield and tensile strength of the ECAPed material reached 340 MPa and 445 MPa, respectively, while maintaining a significant uniform elongation of 14%. Wear resistance results demonstrated that the wear rate, wear depth and width of the ECAPed material decreased in comparison with the solution-treated (SST) and peak-aged (T6) conditions under a load range of 5–25 N. The adhesive wear that occurs in the undeformed specimens at 10 N does not appear in the ECAPed specimen at the same load, indicating that the ECAPed specimen delay the appearance of more serious wear mechanisms under certain loads. The cooperative interaction of high density nano-scale β" precipitates and dislocations resulted in a combination of super-high strength and good work hardening ability which suppressed the extension of cracks between the friction layer and the plastic deformation zone. As a consequence, the combination of ECAP and dynamic aging brings a significant improvement for antifriction performance of the 6061 aluminum alloy.     

新型可焊6005A铝合金的腐蚀行为

采用电化学交流阻抗谱,极化曲线以及浸泡腐蚀实验研究了Cu含量变化对高速列车用6005A铝合金电化学腐蚀行为的影响.结果表明:在商用6005A铝合金基体中添加适量的Cu元素,可有效提高氧化膜的致密性.当添加Cu质量分数为0.4%时,轧制态6005A铝合金电化学交流阻抗图谱中腐蚀反应电阻Rct值较大,双电层电容Q2值较小,极化曲线出现了较宽电位范围的阳极钝化区.但合金自腐蚀电流小幅增加,显示合金局部耐蚀性下降.在质量分数为3.5%NaCl溶液中进行的浸泡实验显示,随着浸泡时间的延长,自制6005A铝合金依次发生点蚀、晶间腐蚀和剥蚀.合金表面氧化膜致密性是影响材料抗腐蚀能力的主要因素.     

Variation of the uniaxial tensile behavior of ultrafine-grained pure aluminum after cyclic pre-deformation

To explore the influence of cyclic pre-deformation on the mechanical behavior of ultrafine-grained (UFG) materials with a high stacking fault energy (SFE), UFG Al processed by equal-channel angular pressing (ECAP) was selected as a target material and its tensile behavior at different pre-cyclic levels D (D=N_i/N_f, where N_i and N_f are the applied cycles and fatigue life at a constant stress amplitude of 50 MPa, respectively) along with the corresponding microstructures and deformation features were systematically studied. The cyclic pre-deformation treatment on the ECAPed UFG Al led to a decrease in flow stress, and a stress quasi-plateau stage was observed after yielding for all of the different-state UFG Al samples. The yield strength σ_YS, ultimate tensile strength σ_UTS, and uniform strain ε exhibited a strong dependence on D when D ≤ 20%; however, when D was in the range from 20% to 50%, no obvious change in mechanical properties was observed. The micro-mechanism for the effect of cyclic pre-deformation on the tensile properties of the ECAPed UFG Al was revealed and compared with that of ECAPed UFG Cu through the observations of deformation features and microstructures.     

Improvement of pitting corrosion resistance for Al-Cu alloy in sodium chloride solution through equal-channel angular pressing

Significant corrosion resistance improvement was achieved in solid-solution treated(T4) Al-Cu alloy after severe grain refinement through equal-channel angular pressing.The bulk ultrafine-grained Al-Cu alloy with grain sizes of 200-300 nm has higher pitting potential(elevated by about 34 mV,SCE) and lower corrosion current density(decreased by about 3.88μA/cm~2) in polarization tests than the as-T4 alloy,and increased polarization resistance(increased by about 5.7 kΩ·cm~2) in electrochemical impendence s...     

Microstructure and mechanical properties of ZE10 magnesium alloy prepared by equal channel angular pressing

ZE10 magnesium alloy was subjected to equal-channel angular pressing (ECAP) up to 12 passes in a die with an angle of 120° between the two channels at 250-300℃. An inhomogeneous microstructure of bimodal grains including fine grains of 1-2 μm as well as coarse grains of about 20μm was obtained after the initial 1-4 ECAP passes. The grain size became increasingly homogeneous with further ECAP processing and the grains were significantly refined to 1-2 ktm after 8 passes and further refined to 0.5-1 μm after 12 passes. The alloy's yield strength changed slightly but the ductility improved greatly initially up to 4-6 passes corresponding to the bimodal grain microstructure. And after the subsequent pressing of more than 8 passes, the tensile strength including yield strength improved while the elongation decreased gradually.     

Zr原子分数对Ti基非晶复合材料腐蚀性能的影响

采用磁悬浮熔炼水冷铜坩埚-负压铜模吸铸法制备了(Ti_0.5Ni_0.5－xZr_x)₈₀Cu₂₀(x=0、0.02、0.04、0.06)非晶复合材料,分析了各种合金试样的相组成,测试了合金试样在人工海水和模拟人体的PBS溶液中的极化曲线,观察了电化学反应后的腐蚀形貌,分析电化学腐蚀产物并进行表征.结果表明:几种合金的组织都是非晶基体与晶体相组成的复合材料,晶体相为B2-Ti(Ni, Cu)奥氏体相和B19’-Ti(Ni,Cu)马氏体相.与晶态TC4合金相比,合金在两种溶液中均具有较好的耐蚀性,且随着Zr元素原子分数的增加,合金的腐蚀抗性也不断增强;当x=0.06时,合金的耐腐蚀性能最为优异,其自腐蚀电位高,为－0.218 V,热力学倾向小不易腐蚀,自腐蚀电流密度较低,为0.912 μA·cm^－2,极化电阻大,为3.4 MΩ·cm²,腐蚀的动力学速率低,且在PBS溶液中合金具有更优异的耐蚀性,在腐蚀形貌中未发现明显的点蚀坑.     

Effects of cupric ions on the corrosion behavior of aluminum alloy 5A02 in ethylene glycol-water solution

The effects of cupric ions on the corrosion behavior of aluminum alloy 5A02 in ethylene glycol-water solutions were studied by potentiodynamic polarization, electrochemical noise (EN), and complementary techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). A positive corrosion potential and increased corrosion current were observed due to the deposition of copper. The results demonstrate that the main corrosion type was pitting and the increasing cupric ion concentration augmented the pitting density. The pits became larger and deeper as a result of the embedment of copper into the surface of the alloy. Cupric ions were preferentially deposited at the defects around the secondary phase, leading to the formation of Al-Cu microgalvanic couples, which increased the corrosion rate. The corrosion rate gradually reached a stable value as the concentration of cupric ions was increased beyond 10 mmol/L.     

3％NaCl溶液中55％Al－Zn－1．6％Si合金镀层电化学参数测定及电偶腐蚀的电化学行为

提出了一种弱极化曲线测量数据计算机处理方法，并计算了５５％Ａｌ－Ｚｎ－１．６％Ｓｉ合金镀层在３％ＮａＣｌ溶液中腐蚀过程的电化学参数，研究了镀件在３％ＮａＣｌ溶液中发生整体腐蚀加速的机理．结果表明，镀层表面微电偶局部腐蚀的发展形成了基体钢与镀层金属的宏观电偶腐蚀，电偶电位Ｅｇ随时间的正移，使镀层金属的溶解电流密度迅速增大，钢基体受到的保护效应减小．     

Corrosion behavior of ultrafine-grained AA2024 aluminum alloy produced by cryorolling

The objectives of this study were to produce ultrafine-grained (UFG) AA2024 aluminum alloy by cryorolling followed by aging and to evaluate its corrosion behavior. Solutionized samples were cryorolled to ~85% reduction in thickness. Subsequent aging resulted in a UFG structure with finer precipitates of Al₂CuMg in the cryorolled alloy. The (1) solutionized and (2) solutionized and cryorolled samples were uniformly aged at 160℃/24 h and were designated as CGPA and CRPA, respectively; these samples were subsequently subjected to corrosion studies. Potentiodynamic polarization studies in 3.5wt% NaCl solution indicated an increase in corrosion potential and a decrease in corrosion current density for CRPA compared to CGPA. In the case of CRPA, electrochemical impedance spectroscopic studies indicated the presence of two complex passive oxide layers with a higher charge transfer resistance and lower mass loss during intergranular corrosion tests. The improved corrosion resistance of CRPA was mainly attributed to its UFG structure, uniform distribution of fine precipitates, and absence of coarse grain-boundary precipitation and associated precipitate-free zones as compared with the CGPA alloy.     

医用可降解Fe30Mn○xCa合金的制备及性能

通过机械合金化、粉末压坯及热挤压的方法制备了医用可降解Fe₃₀Mn_○xCa(x=0，1.5，3.0，4.5)合金棒材，运用金相显微镜、SEM、拉伸测试、电化学测试和SBF浸泡腐蚀等研究了Ca的添加对合金组织及性能的影响.结果发现，Fe₃₀Mn_○xCa合金均由奥氏体组成，且随着Ca质量分数增加，该合金硬度增加，伸长率和强度降低，降解性能显著提高，腐蚀速率从Fe₃₀Mn的0.1130mg/(cm²·d)增至Fe₃₀Mn_4.5Ca的0.2260mg/(cm²·d).细胞毒性实验表明其生物相容性为0～1级.     

Studies on Wear and corrosion resistances of carbon nitride thin films on Ti alloy

0　IntroductionArtificialarthrosiseshavebeenwidelyusedintheoperatorsclinicalsurgeriesforthepatientswhosearthrosiseswerese riouslyseverelydamaged.Butmostofartificialarthrosisescanon lybeusedforabouttenyearslongduetotheseriousabrasion .Forthisreason ,theimprovementofthelongevityofartificialarthrosisbecomesanimportantsubjectofstudy .TheartificialarthrosisesbeingmadeupofTialloyTC4(Ti 6Al 4V)andthepolythenewithultrahighmolecularweighthavegreatpotentialitiesonim provinglongevitybecauseTC4canreac…     

添加Ni对Mg—AI储氢合金电化学性能的影响

为探究添加Ni对Mg～A1储氢合金电化学性能的影响机制,笔者采用机械合金化在氩气保护下经高能球磨制备了添加5％Ni的MgssAl42储氢合金,利用电化学方法研究了球磨时间和添加Ni对其放电容量及腐蚀电化学性能的影响。结果表明：目前研究的储氢合金放电容量与球磨时间有关,随球磨时间的延长先变大,球磨10h时放电容量最大为408．5mAh·g^-1,此时的放电时间为490min,随后逐渐减少;储氢合金出现二次钝化现象,但二次钝化区间较短,腐蚀速度与球磨时间有关,球磨1h时腐蚀速度最低,此时的腐蚀电流密度为1．28×10^-5A·cm^-2;交流阻抗谱由单容抗弧组成,极化电阻随球磨时间的延长先减小再增大而后减小。添加5％Ni后合金放电容量最大,但腐蚀速度有所加快。     

Cl-作用下2A12铝合金在大气环境中腐蚀初期的微区电化学行为

用扫描开尔文探针(SKP)和局部电化学交流阻抗(LEIS)技术,研究了2A12铝合金在盐雾腐蚀实验早期阶段的腐蚀行为和电化学过程.结果表明,盐雾实验初期,铝合金表面出现点蚀坑,Cl-对铝合金腐蚀有显著的加速作用,随盐雾时间延长,点蚀扩展.扫描开尔文探针的测试结果显示,在盐雾腐蚀过程的初期,金属表面阴极区和阳极区不断发生变化,呈现局部腐蚀的特征.随着盐雾时间的延长,试样表面电位逐步正移,并出现明显的阴极区和阳极区.局部电化学交流阻抗的测试结果表明,试样表面的局部电化学阻抗随盐雾时间的延长而有所增加,但分布较为分散.这说明在腐蚀过程的初期,2A12铝合金表面不断生成腐蚀产物,对腐蚀反应产生阻碍作用.     

氯化镧对2024铝合金缝隙腐蚀的缓蚀作用

为了降低2024铝合金在海水中的缝隙腐蚀敏感性,采用浸泡和动电位极化、电化学阻抗等研究了氯化镧(LaCl3)对该铝合金缝隙腐蚀行为的影响,并通过原子力显微镜对缝隙试样内、外腐蚀产物膜的形貌进行了观察.结果表明:当海水中LaCl3的质量浓度超过2.0 g.L-1以后,它能有效地减缓2024铝合金在海水中的缝隙腐蚀.这主要是因为LaCl3减缓了缝隙的阴极反应速率,降低了缝隙内、外的氧浓度差,且缝隙内、外生成的均匀致密的腐蚀产物膜降低了Cl-侵蚀性,这些因素抑制了缝隙的萌生与扩展,提高了2024铝合金在海水中的抗缝隙腐蚀能力.     

锌铝合金镀层表面低铬钝化膜的研究

探索了低浓度铬酸盐钝化处理在热浸镀锌铝合金镀层上的应用·采用盐雾试验、电化学腐蚀试验和人造海水浸泡试验对锌铝合金镀层表面低浓度铬酸盐钝化膜的耐蚀性进行了测试,并借助ＸＰＳ和ＡＥＳ对钝化膜的组成进行了分析·结果表明,锌铝合金镀层经低铬酸盐钝化处理后耐蚀性得到了显著提高,钝化膜的元素组成(原子数分数,％)为:Ｓ５－５,Ｎａ３－４,Ｃ１１－８,Ｔｉ７－９,Ｏ４１－６,Ｃｒ１３－７,Ｚｎ１６－０·     

AZ40镁合金在模拟海水介质中的腐蚀行为

采用Tafel极化曲线、电化学阻抗谱方法研究了AZ40镁合金在模拟海水介质中的腐蚀行为,采用光学显微镜、扫描电子显微镜对腐蚀形貌进行了观察,结合介质pH值测量,讨论了腐蚀机理。结果表明,AZ40镁合金在模拟海水介质中的耐蚀性能较差;腐蚀自发发生,初期以点蚀为主要特征;由于Mg(OH)2等腐蚀产物存在较多缺陷,且分布不均匀,不能有效阻止腐蚀的发展,致使腐蚀扩展迅速,合金表面在短时间内就被严重破坏。     

Cu48Zr43Al9合金在0.05mol/L Na2SO4介质中腐蚀电化学行为研究

采用真空电弧熔炼法制备Cu48Zr43Al9晶态合金及铜模铸造法制备Cu48Zr43Al9非晶合金。通过极化曲线和交流阻抗谱技术研究了Cu48Zr43Al9晶态和非晶态合金在0.05 mol/LNa2SO4溶液中腐蚀电化学行为。结果表明,在0.05 mol/LNa2SO4溶液中,Cu48Zr43Al9晶态和非晶态合金的交流阻抗谱均呈单容抗弧,实验结果说明合金的腐蚀过程是由电化学控制。与非晶合金相比,腐蚀电位负移,晶态合金的电荷传递电阻减小,腐蚀电流密度变大,腐蚀速度加快。在0.05mol/LNa2SO4溶液中,Cu48Zr43Al9非晶态合金具有良好的耐腐蚀性能,这是因为非晶态合金不具有晶格缺陷,结构均一稳定。     

晶粒细化对Cu-20Ag-30Cr合金在HCl溶液中腐蚀电化学行为的影响

采用机械合金化通过控制球磨时间制备不同晶粒尺寸的三元合金粉末,然后分别以真空热压工艺制备常规晶粒尺寸和纳米晶粒尺寸的Cu-20Ag-30Cr合金块状合金。并且利用PARM273A和M5210电化学综合测试系统对两种合金进行电化学腐蚀测试,通过测定电化学极化曲线和交流阻抗谱研究了常规晶粒尺寸和纳米晶粒尺寸的Cu-20Ag-30Cr合金在不同浓度HCl溶液中的腐蚀电化学行为。结果表明随着HCl浓度的增加,腐蚀电流密度随之持续增大,自腐蚀电位持续负移,传递电阻持续减小,表明合金的腐蚀程度加剧,合金的耐腐蚀性能减弱;在相同浓度的HCl溶液中,纳米晶粒尺寸的Cu-20Ag-30Cr合金的腐蚀电流密度明显高于高于Cu-20Ag-30Cr合金,表明经过晶粒细化合金腐蚀速度加快,其耐腐蚀性能下降。