Site preference and alloying effect of tungsten in the μ phase of Co7Mo6

The electronic structures of the μ phase of Co₇Mo₆ were investigated by means of first-principles calculation based on the density functional theory. The calculated equilibrium lattice parameters of Co₇Mo₆ are in good agreement with the experimental results. The results of calculation reveal that the addition of tungsten (W) promotes the stability of the μ phase of Co₇Mo₆ and W tends to participate in its formation. Through analysing the calculated electronic structure (partial density of states and charge density difference), it can be noted that a strong interaction exists due to d–d hybridization. Also, the majority of the atoms may contribute their valence electrons to the formation of metallic bonds in binary and ternary systems. Furthermore, the calculated results show that the doped W atom prefers to occupy the Co site in Co₇Mo₆ μ phase.     

Structure of a phase induced with Xe-ion irradiation-implantation in γ-TiAl

A phase transformation in γ-TiAl intermetallic alloy was found to be induced with 50keV Xe-ion irradiation-implantation at doses larger than 2.2 x 10¹⁸ ions m^-2 at room temperature. The structure and the chemical composition of the induced phase were investigated with high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The zones of the induced phase have sizes up to about several tens of nanometres. The phase has a hexagonal structure with a = 0.286 nm and c = 0.462nm. The crystallographic orientation relationship between the phase (P) and the gamma-TiAl matrix is (001)_P//(111)_γ and \[100]_P//[011]_γ. The \[Al]/[Ti] atomic composition ratio in the phase is analysed to be 56/44, slightly different from that of the matrix, 51/49. These results suggest that the induced phase is an Al solid solution of α-Ti alloy phase, which has different structural parameters and chemical composition from those of the reported phase. It is suggested that the size of the ions is important in the phase transformation.     

Extraordinary plastic behaviour of the γ′ precipitate in a directionally solidified nickel-based superalloy

The deformation behaviour of the γ′ precipitate in a directionally solidified nickel-based superalloy is investigated using microscopic observations after tensile testing at room temperature. It is found that coarse γ′ precipitates (604 nm) are sheared by strongly coupled dislocations, and some γ′ precipitates are elongated to approximately 3–6 times of their original lengths. It reveals that, at room temperature, the γ′ precipitate within the experimental superalloy has a significant plastic deformation capacity in comparison with Ni₃Al bulk alloys. Based on the experimental observations, the extraordinary plastic behaviour of the γ′ precipitate is analysed.     

Stacking of hexagonal layers in the structure of β-Mg2Al3

An analysis of cross-sections perpendicular to the main diagonal of a cubic elementary cell of a Samson structure–β-Mg₂Al₃ has been conducted. It has been proved that all skeleton atoms, i.e. which occupy their positions with probability of 100%, form a framework of hexagonal planes. These planes are a part of three domains shifted with respect to each other by one-third of the length of cube's diagonal. Space between domains is filled up by clusters with partially occupied atomic positions. For hexagonal domains, the elementary cell and positions of decorating atoms have been determined.     

Study of γ/γ′ interfacial width in a nickel-based superalloy by scanning transmission electron microscopy

The γ/γ′ interfaces are thought to play an important role in determining the mechanical properties in single-crystal nickel-based superalloys. In this article, interfacial width in DD6, one second-generation single-crystal superalloy containing 2 wt% Re, has been studied by means of scanning transmission electron microscopy. From an atomic resolution high angle annular dark field image, both compositional interfaces and order–disorder interfaces are studied, and it is first found that the interfacial width of chemical composition is same with that between the ordered and disordered phases.     

Formation of Al3Ni2-type nanocrystalline τ 3 phases in the Al–Cu–Ni system by mechanical alloying

An elemental powder mixture of Al (70 at.%), Ni (15 at.%) and Cu (15 at.%) was milled in a high-energy ball mill for various times ranging from 10 to 100?h to form ternary intermetallic alloys. X-ray diffraction and transmission electron microscopy techniques were employed for characterization of the samples. The dissolution of the individual elements into an alloy led to the formation of a τ₃ vacancy-ordered phase after 100?h of milling. This phase was found to be quite stable against milling, and no other crystalline and amorphous phases could be detected. The powder after 100?h of milling was found to contain mostly τ₃ nanophases with partial ordering, and with crystallite sizes in the range 10–20?nm along with a lattice strain of ～0.675%. The milled powder, after annealing at 700°C for 20, 40 and 60?h, revealed the formation of a strain-free and ordered τ₃ phase with a crystallite size of 80?nm, indicating grain coarsening. It is interesting to note that the mechanical energy imparted during milling could not completely destroy the vacancy ordering in the τ₃ phase, unlike other stoichiometric Al–Cu–transition metal (TM) systems, where the disordered B2 (bcc) phase is commonly observed instead of any vacancy-ordered phases.     

Precipitate characteristics and selected area diffraction patterns of the β′ and Q′ precipitates in Al–Mg–Si–Cu alloys

In this study, the precipitate characteristics and selected area diffraction patterns (SADP) of the β?′ and Q?′ precipitates formed at the over-aged state of Al–Mg–Si–Cu alloys are systematically investigated by means of high-resolution transmission electron microscopy and transition matrix. The β?′ precipitates have two cross-sections, rectangle-shaped and round-shaped aligned with [0?0?1]_Al direction, but only rectangle-shaped cross-section exists for Q?′ precipitates. And, both of them have 12 variants and orientations with Al matrix. However, there are only three different zone axes, [0?0?0?1]_β?′, [1?4?5?0]_β?′, and [5?4?1?0]_β?′ for β?′ precipitates, and [0?0?0?1]_Q?′, [1?4?5?0]_Q?′, and [3?2 1?0]_Q?′ for Q?′ precipitates, parallel to the [0?0?1]_Al direction when they are precipitated from the Al matrix, respectively. Then, a new [0?0?1]_Al SADP model, which superposes diffraction patterns of the β?′ and Q?′ precipitates, is established. Furthermore, some “cross-shaped” diffraction streaks appeared at over-aged state can be explained reasonably by this model, which is good in agreement with the experimental data.     

Structural characteristics of a high-quality Al?Ni?Ru decagonal quasicrystal with 1.6nm periodicity,studied by atomic-scale electron microscopy observations

We report the structural characteristics of a high-quality stable decagonal quasicrystal (D phase) with 1.6nm periodicity, formed in Al₇₅Ni₁₅Ru₁₀ alloy annealed at 890°C for 24h. The tiling structure and the arrangement of transition-metal atoms (Ru and Ni) in this Al-Ni-Ru D phase have been clearly revealed by high-resolution electron microscopy (HREM) and by highangle annular detector dark-field (HAADF) scanning transmission electron microscopy (STM) respectively. On the basis of the HREM and HAADF STM observations, the relationship between the arrangement of local structural units and the formation of the long-range quasiperiodic tiling structure is discussed.     

Discovery and Revitalization of “Feeling of Hometown” from a Disaster Site Inhabitant's Continuous Engagement in Reconstruction Work: Ethnographic Interviews with a Radiation Decontamination Worker Over 5 Years Following the Fukushima Nuclear Power Plant Accident1

After hometown loss due to the Fukushima Nuclear Power Plant accident, many radiation decontamination workers started to engage in the reconstruction of their hometown. However, little is known regarding the meaning of experience of engaging in such work. We describe the process of such experience through a series of ethnographic interviews over 5 years with a radiation decontamination worker. The process was classified into the following three periods: “recovery of lost land by inhabitants' own hands,” “goal loss and semiotic trap in pursuit of recovery,” and “revitalization of feeling of hometown.” Consequently, the informant overcame the contradiction theorized as a “semiotic trap” that radiation decontamination for physical recovery would make his return to home impossible, and updated his narrative to the revitalization of “feeling of hometown” through continuous engagement in the work by creating a sense for transplacement, in which the individual focuses on the psychological aspects of his/her hometown instead of the physical aspects. Psychological reconstruction for disaster victims requires the discovery and revitalization of feeling of hometown rather than the completion of physical reconstruction.     

A Review of “Play Therapy with Children in Crisis: Individual,Group and Family Treatment, 3rd Edition”

Abstract

Lesbian, gay, and bisexual (LGB) emerging adults face additional stressors due to discrimination. Emerging adults (n?=?667) drawn from Waves I and III of The National Longitudinal Study of Adolescent to Adult Health (Add Health) were used to assess how parent-child relationships moderated marijuana and illicit drug use. Sexual minorities with strong relationships with mothers had significantly lower odds of using marijuana, but significantly higher odds of using marijuana (but lower odds of using illicit drugs) when they had a stronger relationship with their father. Implications include improving parent-child relationships and identifying additional coping methods for LGB youth.     

The Prophet’s Letter to al-ʿAlāʾ b. Al-Ḥaḍramī: An Assessment of Its Authenticity in Light of the Covenants and the Correspondence with the People of Yemen

The letter to al-?Alā? b. al-?a?ramī embodies a number of parallels to the covenants and to the Prophet Mu?ammad's correspondence with the people of Yemen. This study examines the different versions of the letter that have come down to us from the Musnad of al-?ārith b. Abī Usāma and from a recension from al-?abarānī's Al-mu?jam al-kabīr to reconstruct a critical edition. Having translated the critical edition and analysed its contents, the study then concludes that the letter is in all likelihood authentic and that it is, generally speaking, textually accurate. The implication of this is that the letter and the covenants represent mutual attestations of one another and that the religion of Islam was well-established, having attained a great level of maturity in the Prophet's lifetime.