La 对非晶 Ni_(63)Zr_(37)合金表面状态的影响

采用俄歇电子能谱和 X 射线光电子能谱,并结合氩离子原位溅射剥层研究了非晶 Ni_(63)Zr_(37)及Ni_(63)Zr_(32)La_5合金条带自由侧和贴辊侧的表层成分分布及元素的化学状态。结果表明,非晶 Ni_(63)Zr_(37)合金条带贴辊侧氧化层较自由侧厚且 Zr 的表面偏聚较为显著;加入 La 后,显著地改变了 Ni_(63)Zr_(37)合金条带两侧的表面状态;在合金条带表面及近表面,Ni 以金属态弥散分布在 Zr 和 La 的氧化物上,其电子状态受氧化物的影响;条带表层 Zr 的氧化物由 ZrO_x(1相似文献   

非晶软磁合金Co_(65)Fe_4Ni_2Si_(15)B_(14)的纳米晶化动力学研究

采用差示扫描量热分析(DSC)和X射线衍射技术(XRD)研究了非晶态合金Co_(65)Fe_4Ni_2Si_(15)B_(14)的非等温晶化动力学.结果表明,初始晶化的晶化峰值温度T_p与升温速率β呈线性关系:T_p=11.49lnβ+795.43.采用Kissinger和Doyle-Ozawa方法计算了表观晶化激活能E_a,分别为471.68kJ/mol和461.50kJ/mol.进一步研究发现,该非晶合金的晶化为多阶段的连续形核直至饱和的过程;当进入稳定晶化阶段时,剩余非晶的局域晶化激活能逐渐下降,非晶基体的热稳定性降低,这是由B原子的高温扩散导致的.同时,局域Avrami指数n(α)也反映了不同晶化阶段的形核长大机制.     

Surface Layer of Ni_(68)P_(18)Cr_(14) Amorphous Alloy

In Ni_(68)P_(18)Cr_(14) amorphous alloy, the dominant component elements Ni and P were in lower contentin the surface layer, while Cr was enriched. There was a P enrichment region just below the surfaceoxide layer, which was supposed to enhance the surface segregation of Cr. Nickel was less oxidizedthan Cr.     

Surface Characterization of Ni_(64)P_(20)Fe_(16)Amorphous Alloy by X-ray Photoelectron Spectroscopy and Auger Electron Spectroscopy

The nature of the native oxides formed on thesurface layer of amorphous alloy Ni_(64)P_(20)Fe_(16)hasbeen studied by X-ray photoelectron spectroscopy(XPS)and Auger electron spectroscopy(AES)withdepth profiling by ion bombardment.There aregreat distinctions in compositions and chemicalstates between the surface layer and the bulk.Themain constituents Ni,P and Fe are lower in the sur-face layer,and they are mostly in oxidized states,whereas C,O and N are enriched in the surface lay-er.The thickness of surface oxide layer isapproximately 20 nm,this layer was assumed to beof great significance to various properties of amor-phous alloy Ni_(64)P_(20)Fe_(16),expecially to the chemicaland catalytic properties.Experiments proved thattransitional element Fe cannot improve oxidationresistance of the amorphous Ni-P system.     

氢对Ni25Ti50Cu25记忆合金马氏体相变的影响

利用金相,X－射线,DSC,透射电子显微镜研究了氢对Ni25Ti50Cu25合金马氏体相变的影响,结果表明,当氢含量高时,氢与全金元素形成氢化物,与氧化物共存的李晶亚结构马氏体失去热弹性,当氢含量低329ppm时,氢固溶于合金中,随氢含量增加,马氏体相变温度降低,氢使马氏体在热循环过程中发生稳定。     

机械研磨 Ni_(50)B_(50)合金形成非晶的过程

本文研究了机械研磨 Ni_(50)B_(50)合金非晶的形成过程。唯象地提出用 J-M-A 方程描述此过程,并作了简单的讨论。     

Al的添加对Mg2Ni储氢合金结构和氢扩散能力的影响研究

采用烧结-机械球磨二步法制备了Mg2-xAlxNi(x=0、0.3)储氢合金材料,研究了Al元素的加入对Mg2Ni储氢合金结构和氢扩散能力的影响.XRD和SEM研究表明Al 元素的加入会使储氢合金产生Al3Ni2和Mg3AlNi2新相,并且在表面覆盖分布各异的棱角多边形颗粒,利用循环伏安法测定了Mg2-xAlxNi(x=0、0.3)储氢电极的氢扩散系数,结果表明:Al元素的加入能显著改善Mg2Ni储氢合金结构,提高了氢扩散能力.     

Ductilization of Ni_3Al by Alloying with Substitutional Elements

This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binaryalloys with hypostoichiometric compositions show appreciable ductility at room temperature whenthe samples are prepared by recrystallization annealing after cold pressing,although the alloys withstoichiometric and hyperstoichiometric compositions remain brittle.Melt-spun ribbons withhypostoichiometric compositions contain fine anti-phase domains (APDs),while no APD can beseen in melt-spun ribbons with a hyperstoichiometric composition.The ductility inhypostoichiometric Ni_3Al alloys is associated with low ordering energy of the alloys.The addition ofternary elements,which have been classified as γ formers such as Pd,Pt,Cu,Co and Ag.improvesductility of Ni_3Al alloys.Correspondingly,the microstructure of the melt-spun ribbons consists offine APDs.The addition of γ' formers such as Si,Ti,Zr,V,Nb and Ta leads to brittle intergranular frac-ture.No APD was observed in the melt-spun ribbons of these ternary alloys.     

熔体快淬对纳米晶和非晶Mg20Ni10-xCox(x≈0～4)合金电化学贮氢性能的影响

为了改善Mg2Ni型合金的电化学贮氢性能,用Co部分替代合金中的Ni.用快淬工艺制备了纳米晶和非晶Mg20Ni10-xCox(x=0、1、2、3、4)贮氢合金,分析了铸态及快淬态合金的微观结构,测试了合金的电化学贮氢性能.研究了Co替代Ni及快淬工艺对合金电化学贮氢性能的影响.结果表明,Co替代Ni不改变合金的Mg2Ni主相,但形成了第二相MgCo2.在快淬(x=0)合金中没有发现非晶相,但快淬(x=4)合金显示了纳米晶、非晶结构,表明Co替代Ni提高了Mg2Ni型舍金的非晶形成能力.熔体快淬显著的改善了合金的电化学贮氢性能,合金放电容量和电化学循环稳定性均随淬速的增加而增加.     

La0.67Mg0.33Ni3.0-xAlx(x=0～0.3)贮氢合金的相结构及电化学性能的研究

研究了Al元素对合金La0．67Mg0．33Ni3．0中Ni的替代对舍金的微观组织结构及电化学性能的影响。X射线衍射(XRD)分析结果表明La0．67Mg0．33Ni3．0合金由PuNi3型(La，Mg)Ni3相和Ce2Ni2型(La，Mg)2Ni7相组成，Al元素加入后，开始出现CaCu5型LaNi5相，随着Al含量的增加，LaNi5相逐渐增多，当x=0．3时，LaNi5相成为合金的主相，合金La0．67Mg0．33Ni3．0中Al的X荧光元素面分布图像表明了Al元素主要进入LaNi5相中，说明Al是一种LaNi5相形成元素；电化学测试表明，随着Al含量的增加，合金的最大放电容量依次下降，4种合金的最大放电量分别为392、324、267和252mAh／g，活化次数变化不大(2～3次即可活化)，循环稳定性先增加后下降。     

金属玻璃Pd_(77.5)Ni_(6.0)Si_(16.5)的晶化过程

本文报道了三元金属玻璃Pd_(77·5)Ni_(5·)Si_(·5)经不同温度退火后的透射电子显微镜观察结果。初步确定了Pd_(77·5)Ni_(6·)Si_(16·s)的晶化过程和亚稳相的结构。由于Ni元素的加入,使其晶化过程相对于二元金属玻璃Pd_(su)Si_(2u)变得更加复杂。     

机械合金化制备Mg76-xTi12Ni12Mnx（x=2,4,6,8）合金及其贮氢性能研究

利用机械合金化法制备了Mg76-xTi12Ni12Mnx(x=2,4,6,8)合金,并研究了Mn添加量对合金贮氢性能的影响。结果表明,在Mg76-xTi12Ni12Mnx(x=2,4,6,8)合金中合金相主要由Mg2Ni和Ti2Ni相组成,合金最大贮氢量分别为3.47%、3.32%、3.60%和3.11%(质量分数,下同),合金氢化物的分解热依次为-79.2kJ/mol、-78.0kJ/mol、-73.7kJ/mol和-73.6kJ/mol,添加Mn可降低合金氢化物的稳定性,改善其热力学性能,非晶化不利于提高合金的贮氢性能。     

Ni50Ti50非晶粉末在球磨时的稳定性

将Ｎｉ５０Ｔｉ５０单质混合粉末经机械合金化形成非晶态合，再进一步球磨使其产生晶化。结果表明，晶化产物为Ｎｉ３Ｔｉ金属间化合物。当Ｎｉ５０Ｔｉ５０非晶体加热时，产生的晶化产物有ＮｉＴｉ，ＮｉＴｉ２和Ｎｉ３Ｔｉ三种金属间化合物。本文通过ＤＳＣ差热分析，测定了Ｎｉ５０Ｔｉ５０非晶合金的晶化热及晶化激活能，并讨论了过度球磨时非晶晶化机制。     

Mg-Zn-Ca-Ti非晶合金的非等温晶化动力学

采用机械合金化的方法制备Mg_(48)Zn_(40)Ca_5Ti_7和Mg_(58)Zn_(30)Ca_5Ti_7非晶合金。利用X射线衍射仪(XRD)对其物相进行检测;结合差示扫描量热分析方法(DSC),对试样在不同升温速率下的非等温晶化进行研究。结果表明:Mg_(48)Zn_(40)Ca_5Ti_7和Mg_(58)Zn_(30)Ca_5Ti_7基本形成非晶;随着加热速率的增加,合金结晶峰均向更高温度的方向移动;用Kissinger、Ozawa和Augis-Bennett方法分别计算出Mg_(48)Zn_(40)Ca_5Ti_7和Mg_(58)Zn_(30)Ca_5Ti_7非晶合金的表观激活能Eα,发现Mg_(48)Zn_(40)Ca_5Ti_7非晶合金的Eα在250kJ·mol~(-1)~270kJ·mol~(-1)范围内,Mg_(58)Zn_(30)Ca_5Ti_7非晶合金的Eα在180kJ·mol~(-1)~200kJ·mol~(-1)范围内;Mg_(48)Zn_(40)Ca_5Ti_7非晶合金的Avrami指数n在不同升温速率下均在1左右;Mg_(58)Zn_(30)Ca_5Ti_7非晶合金的Avrami指数n随着升温速率的增加,由2.7减小到1.9。     

机械合金化能量转换与Ni_(50)Ti_(50)非晶合金的形成

本文报道了球磨转速,装球量对 Ni_(50)Ti_(50)单质混合粉机械合金化的影响,并建立模型用于计算工艺条件对球磨能量转换的影响,进而讨论了它与机械合金化相变反应方式的关系。粉末在每次碰撞的变形能过高时,可能形成金属间化合物,而粉末经长时间球磨获得的总能量超过一定值将引起非晶的晶化。     

铸态La0.75Mg0.25Ni3.3Co0.2Six(x=0～0.2)电极合金的电化学与动力学性能

为了提高La-Mg-Ni系A2B7型贮氢合金的电化学循环稳定性,添加少量的Si,用铸造工艺制备了La0.75 Mg0.25 Ni3.3 Co0.2 Six(x＝0、0.05、0.1、0.15、0.2)贮氮合金,分析并测试了其微观结构和电化学性能,以及高倍率放电能力,交流阻杭等动力学性能.结果表明,合金具有多相结构,主相...     

Natural Passivity of Amorphous Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 Alloys

The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.     

Correlation of the Mechanical Properties of Polycrystalline Ni_3Al Alloys with Their Electronic Structure

The electronic structure of Ni_3Al alloys with different B contents has been investigated by measuringthe positron lifetime spectra.The segregation of B atoms to defects could form strong covalentbondings with Ni and Al atoms and make the electronic structure in those locations similar to that inbulk,thus strengthen their cohesion.The interaction of B atoms,which were solid-solutioned in thecrystal lattice of Ni_3Al in a manner of occupying interstitial sites,with Ni and Al atoms resulted in theincrease of the density of valent electrons,thus increased the bonding cohesion in bulk.The im-provement of the mechanical properties of Ni_3Al alloys by B doping was due to both“grain bounda-ry effect”and“bulk effect”of B,which correlated with their electronic structure.     

The effect of hydrogen on crystallization of a Ti<Subscript>50</Subscript>Ni<Subscript>25</Subscript>Cu<Subscript>25</Subscript> amorphous alloy

Two effects not reported previously for the interaction of hydrogen with amorphous metal alloys were observed in a Ti₅₀Ni₂₅Cu₂₅ alloy: (i) hydrogen-induced increase in the crystallization temperature and (ii) suppression of the reverse martensitic transition B19→B2 in the alloy samples hydrogenated upon crystallization.     

Glass-Forming Ability for Nd_(70-x)Fe_(20)Al_(10)Y_x and Nd_(60-x)Fe_(30)Al_(10)Y_x Alloys

The glass-forming ability (GFA) of Nd70-xFe2oAl10Yx and Nd60-xFe30Al10Yx (0< x <15) alloys produced by Cu mold casting was investigated. Except Y=5 at. pct, bulk amorphous Nd70-xFe20Al10Yx alloys up to 2 mm in diameter were obtained. The GFA for Nd60-xFe30Al10Yx alloys, however, was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy. The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3 mm in diameter. The melting temperature or/and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys. The bulk amorphous cylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization. The crystallization temperature, Tg, and the supercooled liquid region, TX, are 776 K and 58 K, respectively. The GFA and thermal stability of the Nd-Fe-AI-Y a