NiMnGaTi铁磁形状记忆合金的马氏体相变和磁性能

对Ni₅₃Mn_23.5Ga_23.5-○xTi_○x(x=0,2,5和8)系列合金的微观组织、马氏体相变及磁性能进行了研究,探究不同制备方法和不同Ti含量对合金性能的影响规律.研究结果表明:随着Ti含量的增加,合金的晶粒变细且析出物数量显著增加,适量的韧性第二相析出有助于改善合金的高脆性,合金的马氏体相变温度和饱和磁化强度均降低.EDS能谱分析表明,Ti掺杂合金的析出物是富Ni和Ti的第二相.对于Ti₀和Ti₂合金,900r/min甩带样品的饱和磁化强度与铸态样品基本相同,但Ti₅和 Ti₈甩带样品的磁化强度明显高于铸态,这是甩带工艺抑制非磁性的第二相析出所致.     

铝掺杂对无钴正极LiNi0.90Mn0.10O2结构及电化学性能的影响

采用共沉淀法将质量分数3%的Al取代Mn掺入二元Ni_0.90Mn_0.10OH₂前驱体中,经高温固相烧结合成一种无Co高Ni三元正极LiNi_0.90Mn_0.07Al_0.03O₂,并通过X射线衍射(X ray diffraction, XRD)、扫描电子显微镜(scanning electron microscope, SEM)、能量弥散射线谱(energy dispersive spectroscopy, EDS)等表征手段进行分析,探讨了Al³⁺掺杂对材料结构及性能的影响。结果表明,引入Al³⁺后,Ni_0.90Mn_0.07Al_0.03OH₂一次颗粒明显变细,对应LiNi_0.90Mn_0.07Al_0.03O₂结晶度明显提高...     

采用焙烧-水浸法从报废锂离子动力电池中回收金属

锂离子动力电池在新能源汽车中已获得广泛应用,其报废后Li、Ni、Co、Mn等金属清洁高效回收对促进有色金属循环利用具有重要意义.从LiNi_0.5Co_0.2Mn_0.3O₂为正极材料的锂离子动力电池中回收Li、Ni、Co、Mn,并采用TG-DSC、XRD、ICP-OES、XPS、热力学分析等研究了回收过程物相演变规律及影响金属回收率的主要因素.结果表明:由LiNi_0.5Co_0.2Mn_0.3O₂与NaHSO₄·H₂O组成的混合物,经过焙烧后Li、Ni、Co、Mn元素的赋存状态发生改变,从不溶于水的复杂金属氧化物形式,转化为可溶于水的金属硫酸盐形式.焙烧产物在一定条件下用水浸出后,Li、Ni、Co、Mn元素以金属离子的形式转移到水溶液中获得回收.混合物的组成、焙烧温度对Li、Ni、Co、Mn元素在焙烧产物中的赋存形式呈现制约关系,也是影响Li、Ni、Co、Mn金属回收率的主要因素.     

Activity coefficient of NiO in SiO2-saturated MnO–SiO2slag and Al2O3-saturated MnO–SiO2–Al2O3slag at 1623 K

As a part of the fundamental study related to the reduction smelting of spent lithium-ion batteries and ocean polymetallic nodules based on MnO–SiO₂slags,this work investigated the activity coefficient of NiO in SiO₂-saturated Mn O–Si O₂slag and Al₂O₃-saturated Mn O–SiO₂–Al₂O₃slag at 1623 K with controlled oxygen partial pressure levels of 10^-7,10^-6,and 10^-5Pa.Results showed that the solubility of nickel oxide in the slags increased with increasing oxygen partial pressure.The nickel in the Mn O–Si O₂slag and Mn O–Si O₂–Al₂O₃slag existed as Ni O under experimental conditions.The addition of Al₂O₃in the Mn O–Si O₂slag decreased the dissolution of nickel in the slag and increased the activity coefficient of Ni O.Furthermore,the activity coefficient of Ni O(γN_(i O)),which is solid Ni O,in the Si O₂saturated Mn O–Si O₂slag and Al₂O₃saturated Mn O–Si O₂–Al₂O₃slag at 1623 K can be respectively calculated asγN_(i O)=8.58w(Ni O)+3.18 andγN_(i O)=11.06w(Ni O)+4.07,respectively,where w(Ni O)is the Ni O mass fraction in the slag.     

粉末冶金Ti–45Al–10Nb合金的高温抗氧化性能

通过粉末冶金法制备了化学成分为Ti–45Al–10Nb的高Nb含量的TiAl合金,并研究了其在850、900和950°C下的抗氧化性能。根据氧化皮形貌和微观结构演变分析,讨论了高温下的抗氧化机理。850°C和900°C的氧化皮结构相似,TiO₂+Al₂O₃混合物覆盖在弥散分布TiO₂+Nb₂O₅的基体层。在950℃时,氧化皮从外部到母体金属分为四层:疏松的TiO₂+Al₂O₃层、致密的Al₂O₃层、致密的TiO₂+Nb₂O₅层和弥散分布TiO₂+Nb₂O₅的基体层。Nb层抑制了Ti原子的向外扩散,阻碍了TiO₂的生长,同时促进形成连续的Al₂O₃保护层,使合金具有长期的高温抗氧化能力。     

Microstructure of Ni–Al powder and Ni–Al composite coatings prepared by twin-wire arc spraying

Ni–Al powder and Ni–Al composite coatings were fabricated by twin-wire arc spraying (TWAS). The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the obtained particle size ranged from 5 to 50 μm. The morphology of the Ni–Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni₃Al, Al₂O₃, and NiO. The Ni–Al phase and a small amount of Al₂O₃ particles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni–Al composite coatings were characterized by SEM, EDS, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and NiAl in addition to a small amount of Al₂O₃. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, NiAl, and Ni₃Al in addition to a small amount of Al and Al₂O₃, and NiAl and Ni₃Al intermetallic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl₃ precipitates and a Ni–Al–O amorphous phase formed in the matrix of the Ni solid solution in the original state.     

Ni_（50-x）Mn_（10＋x）Ga_（30）Cu_（10）系列Heusler合金的结构、马氏体相变和磁性研究

通过实验和第一性原理研究了Ni50-xMn10＋xGa30Cu10（x=0-10）系列Heusler合金的结构、马氏体相变和磁性.实验研究发现,当用Mn原子在化学上替换Ni原子,合金的晶格参数随成分线性增大,相应体系的马氏体相变温度线性降低;理论分析认为,体系合金的单胞尺寸和电子浓度的共同作用使马氏体相变温度随成分变化线性降低直至消失;体系中Mn对Ni原子的替换使交互作用较强的Ni（A,C）-Mn（B）原子对逐渐形成,这增强了磁性原子间总的交换耦合作用,实验观测到体系合金的居里温度随成分逐渐上升.基于KKR-CPA-LDA的第一性原理计算结果表明,在体系合金中Mn原子磁矩始终与Ni原子磁矩保持铁磁排列,且Mn原子为体系分子磁矩的主要贡献者,因此体系合金的分子磁矩随Mn原子数量线性增加,这与实验结果相一致.     

Co离子掺杂La2Ti2-xCoxO7的室温多铁性

通过向传统铁电材料La₂Ti₂O₇中引入磁性Co离子,成功制备出了新型室温多铁材料La₂Ti_2-xCo_xO₇(x=0、0.03、0.05、0.07)。测试结果表明,所有样品均为单相晶体结构,在x射线探测范围内无第二相杂质出现。适当浓度的磁性Co离子掺杂不仅可有效提高材料的饱和铁磁磁化强度,还可有效降低体系漏电流,提高La₂Ti₂O₇绝缘性,进而改善La₂Ti_2-xCo_xO₇铁电性和多铁性。对La₂Ti_2-xCo_xO₇等样品的顺磁、反铁磁和铁磁等复杂磁相互作用的微观机理进行了探讨。铁磁性的产生被认为与氧空位和过渡金属离子3d电子自旋之间的交换耦合作用有关。而对未掺杂的La₂Ti...     

添加Zr和Mn对Mg–2.5wt%Cu–Xwt%Zn (X = 2.5、5和6.5)合金组织和性能的影响

本工作研究了添加量小于1wt%的Zr和Mn对含2.5wt% Cu和2.5wt%–6.5wt% Zn的Mg–Zn–Cu合金的显微组织、力学性能、铸造性能和耐腐蚀性能的影响。通过对硬度和电导率的测量研究,找出具有最佳力学性能的最佳热处理方案。研究表明,由于Zr具有较强的晶粒细化效应,使得合金的屈服强度显著提高。然而,Mn和Zr的存在对合金的断裂伸长率有不利影响。研究结果表明,合金结构中Mg₂Cu阴极相的析出对腐蚀行为产生了负面影响。然而,添加Mn降低了所研究合金的腐蚀速率。当铜含量为2.5wt%,锌含量为5wt%时,合金的力学性能、铸造性能和腐蚀性能得到了最佳的组合。而Mn或Zr的添加可以改善合金的性能;例如,添加Mn或Zr会增加合金的流动性。     

Cu掺杂La0.5Ba0.5CoO3-δ阴极材料动力学性能研究

利用溶胶-凝胶法制备了钙钛矿结构La_0.5Ba_0.5Co_1-xCu_xO_3-δ(LBCC_-x,0≤x≤0.4)氧化物,系统地研究了Cu部分取代Co对LBCC_-x阴极材料的晶体结构、电导率和电化学性能的影响.研究结果表明：Cu掺杂La_0.5Ba_0.5CoO_3-δ增加了晶格体积和氧空位浓度,降低了电极材料的电导率.Cu部分替代Co有效改善了LBCC_-x阴极材料的电化学性能.当温度为750℃时极化阻抗为0.043Ω·cm^-2,La_0.5Ba_0.5Co_0.7Cu_0.3O_3-δ,(LBCC₃)表现出最优的氧还原反应活性.弛豫时间分布(DRT)分析表明,气体扩散是LBCC_-x阴极材料电催化...     

XPS Studies of Magnetic Multilayers

NiO_x/Ni₈₁Fe₁₉ and Co/AlO_x/Co magnetic multilayers were fabricated by reactive RF/DC magnetron sputtering on clean glass substrates and oxidized Si (100) substrates, respectively. The exchange biasing field (H_ex) between NiO_x and Ni₈₁Fe₁₉ as a function of NiO_x oxidation states was studied by X-ray photoelectron spectroscopy (XPS). The oxidation states and the oxide thickness of Al layers in magnetic multilayer films consisting of Co/AlO_x/Co were also analyzed. It is found that the H_ex of NiO_x/Ni₈₁Fe₁₉ films only depends on Ni2+ but not on Ni3+ or Ni. The bottom Co can be completely covered by depositing an Al layer thicker than 2.0 nm. The oxide layer was Al₂O₃, and its thickness was 1.15 mn.     

钐对SmxMn0.3?xTi催化剂NH3选择性催化还原NOx过程中N2选择性的影响

本文研究了Sm对Mn基催化剂NH₃选择性催化还原NO的改善作用。采用共沉淀法制备了一系列Sm_xMn_0.3?xTi催化剂(x = 0, 0.1, 0.15, 0.2和0.3)。活性测试表明,Sm_0.15Mn_0.15Ti催化剂在180?300°C条件下,NO转化率达100%,N₂选择性达87%以上。表征结果表明,Mn基催化剂中添加Sm,抑制了TiO₂和Mn₂O₃相的结晶,提高了比表面积和酸性,其中Sm改性催化剂的比表面积从152.2增加至241.7 m2·g?1。这些作用有利于提高催化活性。X射线光电子能谱(XPS)结果表明,Sm_0.15Mn_0.15Ti的Sm3+/Sm和O_β/O的相对原子比分别为76.77at%和44.11at%,添加Sm增加了表面吸附氧(O_β),降低了Mn4+的表面浓度;程序升温还原H₂(H₂-TPR)结果表明,Sm_0.15Mn_0.15Ti催化剂还原温度提高,H₂消耗量降低至0.3 mmol?g?1。Sm的引入降低了催化剂Mn4+表面浓度,使得该催化剂氧化还原性能降低,进一步抑制NH₃氧化和非选择性催化还原反应生成N₂O,从而提高了催化剂的N₂选择性。原位漫反射红外傅立叶变换光谱(DRIFTs)表明,Sm_0.15Mn_0.15Ti催化剂的NH₃-SCR反应主要遵循Eley?Rideal机制。Sm掺杂增加了Sm_0.15Mn_0.15Ti催化剂的表面吸附氧(O_β),降低了氧化还原性能,提高了Sm_0.15Mn_0.15Ti催化剂的NO转化率和N₂选择性。     

冷变形及退火对Ti_(50)Ni_(45)Cu_5合金组织性能的影响

研究冷变形与退火对Ti50Ni45Cu5(原子数分数,%)合金组织及性能的影响。研究结果表明:冷变形使片状马氏体变细,合金强度增加,使合金的马氏体相变温度和逆马氏体相变温度降低,且冷变形越大,相变温度降低越多;马氏体转变开始温度Ms随着母相B2晶粒尺寸减小而降低,利用热力学推导得出了Ms与母相B2晶粒尺寸关系式。经35%冷变形400℃退火1 h后,合金具有优良的综合性能,其马氏体转变开始温度Ms为45.2℃,马氏体转变终了温度Mf为10.3℃,逆转变开始温度As为49.0℃,逆转变终了温度Af为80.0℃,抗拉强度为1 198.29MPa,伸长率为7.9%。冷变形+400℃/1 h退火Ti50Ni45Cu5合金的马氏体片细小,马氏体孪晶亚结构增多,内耗峰增高。合金在变温过程中发生B2-B19′相变,在应变振幅为2×10-5,振动频率为0.5~4.0 Hz,变温速率为2 K/min时产生内耗峰,内耗峰位置与振动频率无关,峰高随着测量频率的增加而降低,为热诱导相变内耗机制。相变温度降低,内耗峰位降低。     

添加元素对Mg-基非晶合金非晶形成能力和热稳定性的影响

研究Mg₆₀Ni₂₅Gd_15-xNd_x（x=0,7.5,15）和(Mg₆₀Ni₂₅Gd₁₅)_100-xM_x(M=Fe或Co)（x=0,3,5）非晶态合金快淬甩带样品的非晶形成能力(GFA)及热稳定性随成分的变化关系. 结果表明, 用Nd替代Gd可提高Mg₆₀Ni₂₅Gd_15-xNd_x（x=0,7.5,15）合金的GFA和热稳定性, Fe或Co与主元素间的正混合热降低了(Mg₆₀Ni₂₅Gd₁₅)_100-xM_x(M=Fe或Co)合金的GFA和热稳定性.      

热处理对激光选区熔化镍钛合金性能的影响

采用X射线衍射仪(XRD)、差示扫描量热仪(DSC)、维氏显微硬度计和万能力学试验机等,分析了热处理温度对激光选区熔化(SLM)成形镍钛(NiTi)形状记忆合金的物相、相变温度、显微硬度和力学性能的影响．研究表明：随着热处理温度升高,激光选区熔化成形NiTi合金的相变温度先升高(奥氏体转变峰值温度为43.84℃,马氏体转变峰值温度为37℃)后降低(奥氏体转变峰值温度为1.55℃,马氏体转变峰值温度为-27.18℃);当热处理温度为300～500℃时,NiTi合金中产生马氏体组织和Ni₄Ti₃析出相,该析出相强化了NiTi合金基体;当热处理温度为300℃时,NiTi合金的硬度(HV)、拉伸强度分别为251.7和796 MPa,与激光选区熔化成形的NiTi合金相比分别提升了27.84%和31.35%．上述结果表明采用适当的热处理可以调控NiTi合金相变温度,提升其机械性能．     

1623 K时SiO2饱和的MnO–SiO2渣和Al2O3饱和的MnO–SiO2–Al2O3渣中NiO的活度系数

MnO–SiO₂二元系作为废旧锂离子电池、海洋锰结核还原熔炼过程中的基础渣型,测定有价金属（如镍）在渣中的溶解度、活度及活度系数热力学数据十分必要。为此,本文测定了温度1623 K、氧分压10?7,10?6,和10?5 Pa时SiO₂饱和的MnO–SiO₂渣和Al₂O₃饱和的MnO–SiO₂–Al₂O₃渣中NiO的溶解度和活度系数。结果表明:在试验条件下,镍在MnO–SiO₂渣和MnO–SiO₂–Al₂O₃渣中主要以NiO形式存在,且渣中NiO的溶解度随着氧分压增加而增加;向MnO–SiO₂渣中加入Al₂O₃可以降低渣中镍的溶解度,增加NiO的活度系数。此外,SiO₂饱和的MnO–SiO₂渣和Al₂O₃饱和的MnO–SiO₂–Al₂O₃渣中NiO的活度系数（γ_NiO,以纯固体NiO为参考态）可分别按如下公式计算:γ_NiO = 8.58w(NiO) + 3.18; γ_NiO=11.06w(NiO) + 4.07, 其中,w(NiO)为渣中NiO的质量分数。     

全水解制氢用自支撑多孔NixFe–S/NiFe2O4异质结构双功能电催化剂

稳定的非贵金属双功能电催化剂是可再生能源驱动的波动全水电解面临的难题之一。本文在三维碳纤维布上电沉积制备了多孔Ni–Fe金属阵列,并在此基础上进行原位氧化和化学硫化,构建了一种新型的自支撑分级多孔Ni_xFe–S/NiFe₂O₄异质结构双功能电催化剂。研究结果表明,Ni_xFe–S/NiFe₂O₄异质结构催化剂对析氢反应(HER)和析氧反应(OER)都表现出良好的催化活性和稳定性,优异的催化性质与其大比表面积提供丰富的活性位点、异质结构的协同效应、超亲水表面和稳定的自支撑结构密不可分。分析结果证析氧过程异质结构中的Ni_xFe–S转化为金属氧化物/氢氧化物和Ni₃S₂。与商用20wt% Pt/C||IrO₂-Ta₂O₅相比,自支撑Ni_1/5Fe–S/NiFe₂O₄||Ni_1/2Fe–S/NiFe₂O₄在10-500mA/cm2的波动电流密度范围内表现出更好的稳定性和更低的槽电压。在500 mA/cm2的工业电流密度下,Ni_1/5Fe–S/NiFe₂O₄||Ni_1/2Fe–S/NiFe₂O₄的槽电压仅为约3.91 V,比Pt/C||IrO₂–Ta₂O₅ (约4.79 V)降低了约20%。     

Corrosion behavior of low alloy steels in a wet–dry acid humid environment

The corrosion behavior of corrosion resistant steel (CRS) in a simulated wet–dry acid humid environment was investigated and compared with carbon steel (CS) using corrosion loss, polarization curves, X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), N₂ adsorption, and X-ray photoelectron spectroscopy (XPS). The results show that the corrosion kinetics of both steels were closely related to the composition and compactness of the rust, and the electrochemical properties of rusted steel. Small amounts of Cu, Cr, and Ni in CRS increased the amount of amorphous phases and decreased the content of γ-FeOOH in the rust, resulting in higher compactness and electrochemical stability of the CRS rust. The elements Cu, Cr, and Ni were uniformly distributed in the CRS rust and formed CuFeO₂, Cu₂O, CrOOH, NiFe₂O₄, and Ni₂O₃, which enhanced the corrosion resistance of CRS in the wet–dry acid humid environment.     

Effect of Nb on the corrosion behavior of continuous bulk metallic glass-coated steel wire composites

(Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5)_100?xNb_x (at%, x=0 and 8) bulk metallic glasses (BMGs) were coated on the surface of Q195 steel wires by a continuous coating process. The potentiodynamic polarization tests of these BMGs were conducted in 3.5wt% NaCl aqueous solution. It is found that the addition of 8at% Nb into Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 alloy results in the improvement of corrosion resistance with the pitting potential of ?52 mV, the open circuit potential of ?446 mV, and the corrosion current density of 9.86×10?6 mA/cm2. This may be attributed to that Nb is beneficial to passivate and stabilize Zr and Ti.     

Mn掺杂对Fe81Al19合金磁致伸缩和输运性质的影响

为改善并提高Fe-Al磁致伸缩合金的性能, 熔炼制备Fe_81-xMn_xAl₁₉(x=0~24)系列合金多晶块体, 并研究Mn元素掺杂替代对Fe₈₁Al₁₉合金的结构、 磁性、 磁致伸缩及输运性质的影响.  结果表明: Fe_81-xMn_xAl₁₉系列合金的磁致伸缩系数随Mn元素质量分数的增加而降低, 这是由生成有序第二相和磁能积密度降低所致; Mn元素掺杂提高了Fe-Al多晶合金的电阻率和Fe\|Al磁致伸缩合金的交流频率使用范围; Mn元素掺杂替代降低了Fe-Al多晶合金的各向异性, 提高了低场磁致伸缩效应.