Mössbauer studies of hyperfine fields in disordered Fe2CrAl

Heusler-like alloy Fe₂CrAl was prepared and studied. Structure determination was done by X-ray. The structure was found to conform to the B₂ type. Magnetic hyperfine fields in this sample were studied by the Mössbauer effect. The Mössbauer spectra were recorded over a range of temperature from 40 to 296 K. The Mössbauer spectra showed the co-existence of a paramagnetic part with a magnetic hyperfine portion at all recorded temperatures. Even with the distribution in the magnetic hyperfine field, the average hyperfine field follows the (T/T _c)^3/2 law. The paramagnetic part of the hyperfine field is explained in terms of the clustering of Cr atoms.     

Theoretical study of aging effects on LaNi<Subscript>5</Subscript> tritium storage

The electronic structure and energy of La₂Ni₁₀H₁₂ and La₂Ni₁₀H₁₁He (He is at tetrahedral, octahedral or twelve-face polyhedral interstitials) double cells have been calculated using the density functional theory. Their equilibrium structure, energy bands, electronic density of states (DOS) and X-ray diffraction are presented and discussed. The results indicate the helium-3 produced due to the decay of tritium is most possibly sited at twelve-face polyhedral and octahedral interstices and changes the thermodynamic properties of LaNi₅ tritide system. The changes due to aging such as the reduction in the isotherm plateau pressure, increase of the isotherm plateau slope, and appearance of deeply trapped hydrogen are caused not only by the lattice expansion, but also by modification of the electronic structure due to the presence of He.     

Evolution of ZnO nanostructures by non-catalytic growth process on steel alloy substrate: Structural and optical properties

Various kind of ZnO nanostructures such as nanowires, nanonails and nanocombs were synthesized by the thermal evaporation process onto the steel alloy substrate without the use of metal catalyst or any additives. Detailed structural characterizations indicated that the grown products possess a single crystallinity with the wurtzite hexagonal crystal structure. Presence of strong optical-phonon E₂ mode, in all the cases, presents the good crystallinity with the wurtzite hexagonal phase for the deposited products. Additionally, appearance of dominated, strong and sharp UV emission in the room-temperature photoluminescence spectra confirmed the good optical properties for the grown nanostructures. A vapor–solid growth mechanism has been proposed for the growth of the nanostructures.     

固体薄层纵深分析研究——Ⅱ.钢、铝合金和钛合金溅射速率的测定

用PHI 600型扫描俄歇探针、200型台阶仪和Q-920型图象分析仪,测定了35Cr Ni3MoV钢、Al-5.5 Zn-1.4Mg合金和Ti-5Al-2.5Sn合金的溅射速率,提出了对蚀坑分部位确定溅射速率的方法。文中给出了详细的测定结果。     

Alcohol synthesis over bulk aluminium-nickel-copper based catalysts from syngas

The catalytic performance of bulk aluminium-nickel-copper based catalyst was investigated with regard to alcohol synthesis. It was shown that, in spite of forming methanol as the main product, these catalysts are promising for the production of higher alcohols. Higher activation temperature increased the production of higher alcohols. The change of the salt concentration decreased the selectivity, while the pH had basically no effect on the selectivity.     

Investigations of the distribution of elements in phases present in G-AlMg5Si cast alloy with EDX/WDX spectrometers and AES

The mechanical properties of most aluminium alloys depend heavily on chemical composition, casting methods and heat treatment. Alloys of type G-AlMg₅Si are known for good corrosion resistance and mechanical properties at elevated temperatures. Under the designation Hydronalium (Hy 511) they are used for the production of heads for air cooled Diesel engines. To obtain better mechanical characteristics, titanium is added to the alloy. This paper deals with the results obtained during investigations of the distribution of elements in binary eutectic Mg₂Si and ternary eutectic as well as the distribution of titanium in samples of Hy 511, obtained during casting of cylinder heads. Studies of the distribution of the elements were performed using EDX/ WDX spectrometry, and the distribution of titanium was studied also with Auger electron spectroscopy.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Pseudopotential study of lattice parameter and heat of formation for substitutional alloys

Ashcroft’s empty core pseudopotential is applied to the substitutional alloy (K-CS) to calculate the heat of formation and lattice parameter over the entire concentration range. At any concentration the defect crystal is considered to be equivalent to a perfect crystal with a modified lattice parameter and the potential parameter for the defect crystal is calculated by using some suitable interpolation formula. The calculated results agree well with the available experimental results.     

采用超声筛分法分离K136合金中的γ′与η相

利用微孔滤膜作筛分器分离了K136高温合金中的γ＇与η相。对固溶处理和时效处理的一系列样品的分析结果与萃取残渣-X射线定量相分析的结果吻合。     

铽对Ni50Mn29Ga21磁性形状记忆合金抗弯强度的影响

研究了Tb对Ni50Mn29Ga21磁性记忆合金抗弯强度的影响.结果表明,Tb可以通过两种途径提高合金抗弯强度在Tb含量＜0.1%时,Tb利用它的还原性除去合金内容易引起合金脆性的有害元素氧来净化合金;在Tb含量＞0.1%时,Tb除了净化合金作用外,还通过细化晶粒提高合金抗弯强度.     

用原位红外光谱法研究NiB和NiP非晶态合金的还原和苯加氢反应过程

 用化学还原法制备了NiB和NiP非晶态合金催化剂,并用XRD,DSC,SEM和TEM鉴定了样品的非晶性,用ICP测定了样品的组成．在脉冲微反－色谱装置上考察了这两种催化剂催化苯加氢反应的活性．采用在线漫反射傅里叶变换红外光谱研究了这两种催化剂的还原及苯加氢反应过程．结果表明,所制备的NiB和NiP合金均为非晶态,且都是纳米尺度．NiB的粒度要比NiP小,晶化温度也比NiP低,表明Ni与B之间同Ni与P之间的相互作用不同．对苯加氢反应,NiB非晶态合金具有更大的优势,原位红外光谱结果证实催化剂的活性中心与还原态镍有关．