添加RE和Ti元素对Zn-2.5Al-3Mg合金微观结构和耐腐蚀性能的影响

采用XRD、SEM、TEM和XPS等研究了RE和Ti元素对Zn-2.5Al-3Mg合金微观结构和耐蚀性的影响。结果表明,Zn-2.5Al-3Mg合金的微观结构由富Zn相、二元共晶（Zn-MgZn₂/Mg₂Zn₁₁）和三元共晶（Zn/Al/Mg₂Zn₁₁）组成,而含有RE和Ti元素的合金中出现了新相(Ce_1-xLa_x)Zn₁₁和Al₂Ti。电化学阻抗谱表明,相对于Zn-2.5Al-3Mg合金,Zn-2.5Al-3Mg-0.1RE-0.2Ti合金的耐蚀性得到了显著的提高。XPS分析结果表明,RE元素的添加促进腐蚀产物Zn₅(CO₃)₂(OH)₆和MgAl₂O₄的形成,而RE和Ti元素的同时添加促进腐蚀产物 Zn₅(CO₃)₂(OH)₆、ZnAl₂O₄和MgAl₂O₄的形成,且都抑制了疏松多孔ZnO的生成。Zn₅(CO₃)₂(OH)₆、ZnAl₂O₄和MgAl₂O₄能够很好地粘附在试样表面,提供一层致密的保护层,从而提高Zn-2.5Al-3Mg合金的耐腐蚀性。     

从吸附角度观察Mg-Ca合金中Mg2Ca和 α-Mg的氧化：DFT研究

基于DFT计算O₂在α-Mg（0001）和Mg₂Ca（0001）上的吸附过程,以探明Mg-Ca合金中的α-Mg和Mg₂Ca氧化机理。结果表明,在吸附过程中,O₂与α-Mg和Mg₂Ca有很强的相互作用,且均为化学吸附,但Mg₂Ca的吸附结构不如α-Mg的吸附结构稳定。在氧化过程中,O₂与α-Mg和Mg₂Ca中的Ca和Mg原子发生反应,形成Mg-Ca-O氧化膜,从而提高Mg-Ca合金的抗氧化性。但Mg₂Ca的吸附结构稳定性比α-Mg差,因此Mg₂Ca形成的氧化膜对基体的保护作用比α-Mg弱。     

Mn掺杂提高IrO2-Ta2O5 电极在硫酸溶液中析氧的电催化活性

制备了不同 Mn 含量的IrO₂-Ta₂O₅-MnO_x电极。揭示了Mn含量对该类电极的物理和电化学特性的影响。结果表明,涂??覆的IrO₂-Ta₂O₅-MnO_x层由于其凹凸不平的多孔结构而具有较大的比表面积。少量Mn的加入抑制了活性成分IrO₂的结晶,并将其转化为Ir³⁺。适当地用 Mn 代替Ir可以显著提高 IrO₂-Ta₂O₅-MnO_x 电极的电催化性能。高的电催化活性、长的寿命和低的成本得益于 Mn 掺杂的电极具有更大的活性表面积,从而促进了硫酸溶液中氧的析出。     

TiAl合金与GH3039摩擦焊接界面组织

使用GH3039合金作为γ-TiAl与碳钢摩擦焊接的过渡第三体,采用扫描电子显微镜（SEM）和透射电子显微镜（TEM）分析了TiAl/GH3039摩擦焊接接头的界面结构。结果表明,γ-TiAl和GH3039摩擦焊接接头的最大抗拉伸强度能达到400 MPa以上。GH3039一侧热力影响区的塑性变形大于TiAl一侧,并且在两侧均发生动态再结晶。接近GH3039母材相层中的Ni含量几乎不变,接近TiAl母材相层中的Ti含量也几乎不变。在GH3039侧面附近的焊接区中,富Ni和富Cr晶粒的分布是互补的。Ti和Al容易溶于富Ni的晶粒中,而Mn容易溶于富Cr的晶粒中。在结合区中形成的大量富Cr晶粒是体心立方结构的α-Cr。γ-TiAl和GH3039摩擦焊接的典型界面结构为：γ-TiAl+α₂-Ti₃Al/α₂+τ₃/τ₃-Al_1+x-yTi_1+yNi_1-x/τ₃+α-Cr/(Ni, Cr)_ss/GH3039。     

可降解血管支架用Mg-4.0Zn-0.2Mn-0.2Ca微细管的体外降解行为

通过浸泡实验和电化学测试研究了Mg-4.0Zn-0.2Mn-0.2Ca（质量分数）微细管的体外降解行为与腐蚀机理。结果表明,退火处理可以提高微细管的耐腐蚀性。长期浸泡实验表明腐蚀过程相对均匀,退火微细管在Hank''s溶液中的腐蚀速率约为0.30 mm/a。在浸泡初期,退火管材表面生成Mg(OH)₂,形成保护膜,阻碍腐蚀进行。虽然Mg(OH)₂膜上形成的羟基磷灰石（HA）可以进一步降低腐蚀速率,但是镁基体中粗大的第二相会增强电偶腐蚀效应,并且生成的大量氢气,从而破坏HA膜,使腐蚀继续进行。     

CO2 在 δ-Pu(100)表面吸附行为的第一性原理研究

结合密度泛函理论框架内的周期性平板模型,运用第一性原理计算方法研究了CO₂在δ-Pu(100)表面的吸附行为。结果表明,CO₂分子以C端向下和C-Pu、O-Pu多键结合的方式吸附在δ-Pu(100)表面。吸附类型属于强化学吸附,最稳定的吸附构型是H₁-C₄O₄,此时吸附能为-6.430 eV,吸附稳定性顺序为穴位>桥位>顶位。CO₂分子主要和表面Pu原子反应,而与其它3层Pu原子的反应较弱。更多的电子向CO₂ 2π_u轨道转移有利于C-O键的弯曲和活化。此外,CO₂分子和Pu原子之间的化学键主要是离子态,反应机理是CO₂的C 2s、C 2p、O 2s 和O 2p轨道与Pu 6p、Pu 6d、Pu 5f轨道发生了重叠杂化作用,产生了新的键结构。H₁-C₄O₄构型的功函数变化最小,表明其它电子容易从该构型表面逃逸,且需要的能量最小。     

人工时效和腐蚀介质浓度对2A97 Al-Cu-Li合金电化学腐蚀行为的影响

采用动电位极化曲线电化学方法研究了2A97-T3和2A97-T6 Al-Cu-Li合金的耐腐蚀性能,并以第3代典型2060-T8合金、2099-T83铝锂合金和航空用2024-T4高强铝合金为参考对象进行了比较。通过分析电化学参数和腐蚀形貌,发现合金在3种浓度的NaCl溶液中的耐腐蚀性为2A97-T3>2A97-T6>2024-T4>2060-T8>2099-T83。随着NaCl溶液浓度的增加,合金的腐蚀电位（E_Corr）均降低,同时加剧了表面点蚀和晶间腐蚀程度。2A97-T3合金通过进行固溶和双级人工时效处理的共同作用得到2A97-T6合金,此时T₁相数量大大增加且分布更加均匀。因此,热处理工艺降低了2A97铝合金的腐蚀电位,导致2A97-T6合金的耐腐蚀性能略弱于2A97-T3合金。晶间θ相的解体诱导了2A97-T3合金的剥落腐蚀形貌,而2A97-T6合金的点蚀形貌是由晶内T₁相的溶解造成的。     

NdCeFeB快淬带相互作用与磁性能

采用感应熔炼制备名义成分为(Nd_1-xCe_x)_2.4Fe₁₄B (x=0, 0.2, 0.4, 0.6, 0.8, 0.8, 1.0)的快淬带,研究了Ce取代量对快淬带的相组成、磁性能和微观结构的影响。XRD结果表明,所有快淬带均呈现四方结构(Nd, Ce)₂Fe₁₄B相,当Ce取代量超过x=0.6时,快淬带中出现CeFe₂相并且CeFe₂含量随着Ce取代量的增加而增加。快淬带的剩磁、剩磁比（M_r/M_s）和晶格常数随着Ce含量的增加而减小,当Ce取代量为x=0.2时,快淬带的磁性能为矫顽力1.31×10⁶ A/m,最大磁能积103 kJ/m³。通过小回线和δM曲线研究了快淬带的矫顽力机理和晶粒间交换耦合,在每个样品中都观察到正的δM值,证实了交换耦合相互作用的存在。Ce含量为x=0.2时δM最大值达到0.76,说明快淬带晶粒间交换耦合效应最强,这一结果与剩磁比的变化一致。SEM观察发现,Ce取代量的增加恶化快淬带的柱状晶结构。     

空气气氛下碳热还原筛分法制备Magnéli相Ti n O2 n -1

介绍了一种在空气气氛中通过碳热还原筛分法制备Magnéli相（Ti_nO_2n-1，4＜n＜10）低价钛氧化物的方法，研究了还原温度和还原时间对还原产物的物相、电阻率的影响。结果表明，提高还原温度和延长还原时间有利于将TiO₂还原为Magnéli相Ti_nO_2n-1。将Magnéli相Ti_nO_2n-1 (n=4，5) 粉末在1350 ℃下干燥20 min，通过扫描电子显微镜观察，其粒径为0.5~8 μm。在还原温度为1350 ℃时，还原产物的电阻率随还原时间的延长而显著降低。在1350 ℃下还原50 min的产物的电阻率最小，为79.3 Ω?cm，其物相组成几乎全部为Ti₃O₅。     

Ca和Mn添加对铸态及热处理态Al-Mg-Si合金的微观组织、力学性能和导电性能影响

制备了Al-0.59Mg-0.54Si-X (X=0, 0.253Ca, 0.253Mn)合金来探究微量Ca、Mn添加对铸态、固溶态及时效态Al-0.59Mg-0.54Si-X合金的微观组织、力学性能及导电性能的影响。研究发现,Ca和Mn添加都显著细化了α-Al的晶粒尺寸。Ca能够诱导高密度的Mg₂Si和Al₂Ca颗粒在铸态α-Al晶粒中析出,使合金在铸态下具有最优的力学性能。固溶和时效处理会导致颗粒粗化并且偏聚在晶界,使合金的力学性能急剧下降,但其电导率却增加到了52.44%IACS。Mn添加使得晶界上的粗大β-Al₅FeSi杂质相转化成α-Al(FeMn)Si颗粒,并且诱导Mg₂Si和AlMn颗粒在铸态合金中析出。因此经过固溶和时效处理后的Al-0.59Mg-0.54Si-0.253Mn合金表现出最优的力学性能以及可接受的电导率。     

Effect of yttrium and calcium additions on electrochemical behaviors and discharge performance of AZ80 anodes for Mg−air battery

The effects of yttrium (Y) and yttrium + calcium (Y+Ca) additions on the electrochemical properties and discharge performance of the as-extruded Mg?8Al?0.5Zn?0.2Mn (AZ80) anodes for Mg?air batteries were investigated. The results show that the addition of 0.2 wt.% Y increased the corrosion resistance and discharge activity of AZ80 anode. This was attributed to the fine and spherical β-Mg₁₇Al₁₂ phases dispersing evenly in AZ80+0.2Y alloy, which suppressed the localized corrosion and severe “chunk effect”, and facilitated the rapid activation of α-Mg. Combinative addition of 0.2 wt.% Y and 0.15 wt.% Ca generated grain refinement and a reduction of the β-Mg₁₇Al₁₂ phase, resulting in a further enhancement in discharge voltage. However, the incorporation of Ca in Mg₁₇Al₁₂ and Al₂Y compounds compromised the corrosion resistance and anodic efficiency of AZ80+0.2Y+0.15Ca anode. Consequently, AZ80+0.2Y anode exhibited excellent overall discharge performance, with the peak discharge capacity and anodic efficiency of 1525 mA·h·g^?1 and 67% at 80 mA/cm², 13% and 14% higher than those of AZ80 anode, respectively.     

Understanding the corrosion behaviour of the magnesium alloys EV31A,WE43B,and ZE41A

The corrosion rates of the Mg alloys immersed in 3.5 wt% NaCl solution saturated with Mg(OH)₂ were in the following increasing order: WE43B (0.23 mm/y) < EV31A (0.88 mm/y) < pure‐Mg (1.6 mm/y) < ZE41A (8.5 mm/y). The average corrosion rate for WE43B was somewhat lower than the intrinsic corrosion rate of Mg as shown by high‐purity Mg, attributed to (a) no corrosion acceleration by the small second phase particles, and (b) a more protective surface film. The high corrosion rates of ZE41A were attributed to the presence of a coarse semicontinuous T‐phase, which served as strong cathodic sites.     

Effects of Al content on the corrosion properties of Mg–4Y–xAl alloys

The corrosion performances of Mg–4Y–xAl (x = 1, 2, 3, and 4 wt%) alloys in the 3.5% NaCl electrolyte solution are investigated by electrochemical tests, weight loss measurement and corrosion morphology observation. The results indicate that corrosion modes for the alloys are localized corrosion and the filiform type of attack. With Al concentration increasing from 1 to 4 wt%, the corrosion rate of Mg–4Y–xAl alloys decreases firstly and then increases, and WA42 alloy shows the best corrosion resistance. The addition of Al element to Mg–4Y alloys leads to the formation of Al₂Y and Al₁₁Y₃ intermetallic compounds and reduces the proportion of Mg₂₄Y₅ phase. Corrosion resistance of the Mg–4Y–xAl alloys mainly depends on the size and distribution of the second phases. Besides, the addition of excessive Al can greatly consumes the Y element in the matrix, thus leading to a less protective film on the alloys. The effect of the relative Volta potential changes between the second phases and α-Mg on corrosion resistance of Mg–4Y–xAl alloys is insignificant. The main corrosion products of the Mg–4Y–xAl alloys are Mg(OH)₂, Mg₃(OH)₅Cl·4H₂O, Mg_0.72Al_0.28(CO₃)_0.15(OH)_1.98(H₂O)_0.48, and Mg₄Al₂(OH)₁₂CO₃·3H₂O.     

固溶态和挤压态Mg-xLi-3Al-2Zn-0.5Y(x=4,8,12)合金的显微组织和腐蚀行为

研究固溶态和挤压态Mg-xLi-3Al-2Zn-0.5Y(x=4,8,12,质量分数,%)合金的显微组织和腐蚀行为。结果表明,当锂含量从4%增加到12%,合金基体由α-Mg单相转变为α-Mg+β-Li双相,再转变为β-Li单相。Mg-4Li-3Al-2Zn-0.5Y和Mg-12Li-3Al-2Zn-0.5Y合金具有晶间腐蚀和点蚀的混合腐蚀特征,前者与沿晶界析出的AlLi相有关,后者与第二相与基体之间的高电位差有关。挤压态合金的耐蚀性优于固溶态合金。挤压态Mg-8Li-3Al-2Zn-0.5Y合金具有最低腐蚀速率(P_W=(0.63±0.26)mm/a),主要归因于该合金的第二相分布更均匀、通过牺牲β-Li相形成的保护性α-Mg相和相对完整的更均匀分布的氧化膜。     

Corrosion and discharge behavior of Mg−xLa alloys (x=0.0−0.8) as anode materials

The corrosion and discharge performances of binary Mg−xLa (x=0.2−0.8, wt.%) alloys as anode materials for Mg-based batteries were evaluated. Microstructure, hydrogen evolution, mass loss, electrochemical behavior, and half-cell discharge capabilities were characterized. The results show that the corrosion rate of the Mg matrix was decreased by alloying with La, and this could be attributed to the formation of a protective La₂O₃-containing film on the surface of the alloy. The Mg−0.2La alloy displayed the lowest corrosion rate, i.e., 2.4 mm/a in a 3.5 wt.% NaCl solution, Furthermore, the discharge performance of Mg−0.4La alloy was superior to that of pure Mg and other Mg−La alloys; this could be associated with the modified microstructure of the Mg−0.4La alloy, which decreased the self-corrosion and accelerated the detachment of the discharge products.     

Corrosion properties of ECAP-processed Mg−Al−Ca−Mn alloys with separate Al2Ca and Mg2Ca phases

To investigate the effect of separate Al₂Ca and Mg₂Ca phases on the corrosion properties of Mg?Al?Ca?Mn alloys, OM, SEM, immersion and electrochemical tests were conducted on the as-cast and ECAP Al₂Ca-containing (2Ca) and Mg₂Ca-containing (4Ca) alloys. At the beginning of corrosion, the two as-cast alloys are corroded slowly compared with ECAP alloys. With prolonging the corrosion time, the corrosion of ECAP alloys becomes slighter than that of as-cast alloys, which is mainly ascribed to the dispersion and refinement of the second phase in ECAP alloys. Moreover, the corrosion degree of 2Ca alloys is always slighter than that of 4Ca alloys, suggesting that Al₂Ca phase is more beneficial to the enhancement of corrosion resistance of Mg?Al?Ca?Mn based alloys than Mg₂Ca phase. Finally, based on the examinations of corrosion surface and electrochemical testing results, different corrosion mechanisms caused by the distributions and morphology of Al₂Ca and Mg₂Ca phases are discussed.     

Effects of Ga and Sn on the electrochemical behavior of Mg–6Al–1Zn as anode materials

The microstructure and electrochemical behavior of Mg–6Al–1Zn, Mg–6Al–1Zn–1Ga, Mg–6Al–1Zn–1Sn, and Mg–6Al–1Zn–0.5Sn–0.5Ga as anode materials in a 3.5 wt% NaCl solution are compared systematically. The results show that Sn alloying refines the second-phases of Mg–6Zn–1Al by promoting tiny granular Mg₁₇Al₁₂ phases containing Sn, and inspires their disperse distribution. However, the Ga results in the formation of semicontinuous reticular Ga containing Mg₁₇Al₁₂ phases. The comparison of discharge tests indicates that Mg–6Al–1Zn–1Sn has the highest discharge activity, and Mg–6Al–1Zn–1Ga displays the largest hydrogen evolution corrosion resistance in 3.5 wt% NaCl solution at 298 K. The synergy of Ga and Sn can shorten discharge activation time and promote low discharge potential. In addition, the utilization efficiencies of the alloys decrease as follows: Mg–6Al–1Zn–1Ga > Mg–6Al–1Zn–0.5Sn–0.5Ga > Mg–6Al–1Zn–1Sn > Mg–6Zn–1Al. This study illustrates that the Mg–6Al–1Zn–0.5Sn–0.5Ga alloy has acceptable utilization efficiency and desirable electrochemical activity, which implies that doping Ga and Sn obtains a balance between discharge activity and utilization efficiencies.     

Microstructure,anticorrosion, biocompatibility and antibacterial activities of extruded Mg−Zn−Mn strengthened with Ca

To find suitable biodegradable materials for implant applications, Mg?6Zn?0.3Mn?xCa (x=0, 0.2 and 0.5, wt.%) alloys were prepared by semi-continuous casting followed by hot-extrusion technique. The microstructure and mechanical properties of Mg?6Zn?0.3Mn?xCa alloys were investigated using the optical microscope, scanning electron microscope and tensile testing. Results indicated that minor Ca addition can slightly refine grains of the extruded Mg?6Zn?0.3Mn alloy and improve its strength. When 0.2 wt.% and 0.5 wt.% Ca were added, the grain sizes of the as-extruded alloys were refined from 4.8 to 4.6 and 4.2 μm, respectively. Of the three alloys studied, the alloy with 0.5 wt.% Ca exhibits better combined mechanical properties with the ultimate tensile strength and elongation of 334 MPa and 20.3%. The corrosion behaviour, cell viability and antibacterial activities of alloys studied were also evaluated. Increasing Ca content deteriorates the corrosion resistance of alloys due to the increase of amount of effective cathodic sites caused by the formation of more Ca₂Mg₆Zn₃ phases. Cytotoxicity evaluation with L929 cells shows higher cell viability of the Mg?6Zn?0.3Mn?0.5Ca alloy compared to Mg?6Zn?0.3Mn and Mg?6Zn?0.3Mn? 0.2Ca alloys. The antibacterial activity against Staphylococcus aureus is enhanced with increasing the Ca content due to its physicochemical and biological performance in bone repairing process.     

The effect of Ca on corrosion behavior of heat‐treated Mg–Al–Zn alloy

The effect of 0.5, 1.0, and 1.5 wt% Ca additions on the microstructure and corrosion resistance of the heat‐treated Mg–Al–Zn alloy was investigated. Addition of 0.5 wt% Ca did not form any new phase but suppressed the discontinuous precipitation of the β ‐Mg₁₇Al₁₂ phase by being dissolved in both the second phase and magnesium matrix. In the materials containing higher amounts of Ca, however, metallographic investigation shows that Ca added to Mg–Al–Zn can obviously decrease the size of β ‐Mg₁₇Al₁₂ and forms Al₄Ca intermetallic compounds in the shape of bone‐like morphology. The corrosion tests used include constant immersion technique, and potentiodynamic polarization experiments and salt spray test. Surface examination and analytical studies were carried out using optical and scanning electron microscopy, EDX, and XRD. The results of corrosion tests show that magnesium alloy Mg–Al–Zn with 1.0 wt% Ca addition has the best corrosion resistance behavior.