Relationship of the Yttrium Compounds with the Alloying Method in ODS Ferritic Stainless Steel

The relationship of the yttrium compounds with its alloying method has been studied, the alloying methods studied including MA and CA (Mechanical Alloying and Chemical Alloying). The results show that the compound in CA steel is Y2Ti2O7 but that in MA steel is Y2O3. The statistical analysis confirms that the titanium contents in the two compounds are different apparently. However, the yttrium content maintains constant.

Process of New Phase Nucleation in Alloys

The article presents a generalization of our electron microscopic results got on some binary and ternary alloys based on Ni,Fe or Co.They are considered as the basis for the conclusion that chemical bonds between atoms are realized in alloys according to the principle of pair interaction.This process begins with the separation of the alloy into diffusion micro-pairs already in the liquid state,which makes it possible to consider the liquid state of the alloy as the initial stage of the new phase formation.With a subsequent decrease in temperature,particles of a new phase form inside a diffusion micro-pair.The formation of diffusion micro-pairs and phases within them occurs due to the existence in alloys,along with a metallic bond,of ionic and covalent components of a strong chemical bond at all temperatures of the condensed state.The article shows what exactly needs to be done so that such a branch of science as materials science could get rid of the empirical approach when creating new alloys.

Growth of carbon nanotube arrays on various CtxMey alloy films by chemical vapour deposition method

Carbon nanotube （CNT） arrays were fabricated on Ct-Me-N-（O） alloys with content of Ct in the range of 6-40 at.% by chemical vapour deposition. The Ct was a catalytic metal from the group of the following elements： Ni, Co, Fe, Pd, while Me was a transition metal from the group of IV-VII of the periodic table （where Me=Ti, V, Cr, Zr, Nb, Mo, Ta, W, Re）. Carbon nanotubes were found to grow efficiently on the alloy surface with its composition containing Ti, V, Cr, Zr, Hf, Nb or Ta. The growth of CNTs was not observed when the alloy contained W or Re. Additions of oxygen and nitrogen in the alloy facilitated the formation of oxynitrides and catalyst extrusion on the alloy surface. Replacement of the metals in alloy composition affected the diameter of the resulting CNTs. The obtained results showed that the alloy films of varying thickness （10-500 nm） may be used for the CNTs growth. The resulting CNT material was highly homogenous and its synthesis reproducible.

An investigation of chemically deposited Ni-P alloys by EXAFS and XRD

Five samples of chemically desposited Ni-P amorphous alloys were prepared and inves- tigated.In these amorphous alloys there are Ni-P atom groups in which phosphorus and nickel are connected with strong interaction.Nickel atoms and Ni-P groups are deposited in a random manner on the surface of matrix and a quasilayer structure is formed.The spacing between two layers in alloys resembles that in(111)plane in the nickel crystal.Therefore there is a peak at the same position of 2θ=44.4° as that of the(111)reflection of crystalline nickel in the X-ray powder diffraction pat- tern of alloys.However,the dimension of Ni-P groups is different from that of a nickel atom and the atomic arrangement in the layer is in disorder.These result in the space change and there is a distribution of spacing around the average.As a consequence of distribution of spacings,the peak at 2θ=44.4° is broadened and enhanced as the amount of P increases.

Charged particles:Unique tools to study irradiation resistance of concentrated solid solution alloys

Many multicomponent concentrated solid solution alloys(CSAs),including high-entropy alloys(HEAs),exhibit improved radiation resistance and enhanced structural stability in harsh environments.To study and assess irradiation resistance of nuclear materials,energetic ion and electron beams are commonly used to create displacement damage.Moreover,charged particles of ions,electrons,and positrons are unique tools to create and characterize radiation effects.Ion beam analysis(e.g.,Rutherford backscattering spectrometry,nuclear reaction analysis,and time-of-flight elastic recoil detection analysis),electron microscopy techniques(e.g.,transmission or scanning electron microscopy,and electron diffraction),and positron annihilation spectroscopy have been applied to characterize irradiated CSAs or HEAs to understand defect formation and evolution together with chemical and microstructural information.Their distinctive analyzing power and some perspectives in these techniques are reviewed.In developing structural alloys desirable for applications in advanced reactors,neutron exposure is a critical test but the limitation in achievable high damage levels is,however,a bottleneck.Ion irradiation is often used as a surrogate for neutron irradiation,and the associated reduced transmutations and higher displacements per atom(dpa)rates are desirable for materials research.Nevertheless,cautions need to be taken when relying on ion irradiation results for reactor evaluations.Literature on differences between ions and neutrons is briefly reviewed.In addition,the links to bridge the current advances on fundamental understandings to reactor applications are discussed to lay the groundwork between neutrons and ions for radiation effects studies.

Mixture of Oxides with Different Valence States in Nanotubes

Oxide nanotubes with different diameters and lengths were fabricated on the biomedical Ti2448 alloy by anodic oxidation in neutral electrolyte. Similar to oxide nanotubes fabricated on pure titanium and its alloys, the as-grown nanotubes on Ti2448 also exhibit gradually changing chemical distribution along the direction of tube growth. Furthermore, several kinds of oxides with different valence states （MxOy） are formed simultaneously for each alloying element M, while their volume fractions vary gradually along the tube-growth direction. The findings of this study would provide insight into the effect of valence states on the desired nanotube properties and help develop ways to enhance the properties of the preferred oxide.