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The microstructure evolution of AA2060 Al alloy containing Li during two-stage homogenization treatment was investigated by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), differential scanning calorimeter (DSC), transmission electron microscopy (TEM), mechanical properties and Vickers micro-hardness test methods. The results demonstrate that severe precipitation of θ(Al2Cu) and S(Al2CuMg) phase existed in the as-cast alloy, especially in the center position. Cu elements were concentrated at grain boundary and gradually decreased from the boundary to the interior. Numerous eutectic phases of θ(Al2Cu) and S (Al2CuMg) containing Zn and Ag elements were segregated at grain boundaries. The overheating temperature of the as-cast alloy is 497 °C. After two-stage homogenization treatment, the θ(Al2Cu) and S (Al2CuMg) in the surface, middle and center positions were completely dissolved into the matrix, thus achieved uniform homogenization effect. Moreover, water cooling could prevent the precipitation after homogenization, which provided good performance of the studied alloy. The optimum two-stage homogenization treatment of AA2060 alloy was 460 °C/4 h + 490 °C/2 4 h. The homogenization kinetic analysis was discussed as well.

The composition of precipitates in peak-aged Al-Zn-Mg-Cu alloys with various Zn/Mg ratios has been investigated by atom probe tomography (APT). The results show that the η′ and the T′ phases have different compositions with a similar Zn/Mg ratio in the same alloy. The Zn/Mg ratio within precipitates was shown to be positively correlated with the Zn/Mg ratio in the alloy. Moreover, the size dependency of composition for ageing precipitates in Al-Zn-Mg-Cu alloys has been determined. This study enriches the understanding of precipitate composition relative to that of the bulk in Al-Zn-Mg-Cu alloys. [ABSTRACT FROM AUTHOR]

A new magnetorheological (MR) fluid was synthesized by dispersing Fe84Nb3V4B9 nanocrystalline powders in a nonvolatile ionic liquid (N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate), which is stable from 282K to 573K. The structure, morphology, and magnetization of Fe84Nb3V4B9 nanocrystalline powders prepared by mechanical alloying were analyzed by using an X-ray diffractometer (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscopy (SEM), respectively. The magnetic clusters of the synthesized MR fluid were observed by using a digital microscope, and its MR properties were measured by using a cone-plate type viscometer. The experimental results showed that Fe84Nb3V4B9 nanocrystalline powders with an average grain size of 10–20 nm can be prepared by mechanical alloying. The MR fluid is magnetic-field-responsive, behaves like non-Newtonian fluids, and its magnetorheological properties are influenced by the applied magnetic flux density and the width of magnetic clusters. [ABSTRACT FROM AUTHOR]

The martensite structure and order state of Cu-18Zn-14Al alloy was studied by means of X-ray diffraction. The alloy was subjected to four different quenching treatments. As the quenching rate decreased, the nnn order degree of the alloy increased and the nn order degree remained almost unchanged. The splitting parameter ? = |sin2?1 - sin2 ?2| and the monoclinic angle ß changed very little. In addition, the order state of the alloy was calculated according to its crystal structure model. It is suggested that only the Zn and Al atoms exchange along theb-axis as the nnn order decreases, which slightly influences crystal symmetry and lattice constant. [ABSTRACT FROM AUTHOR]

The microstructure evolution of AA2060 Al alloy containing Li during two-stage homogenization treatment was investigated by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), differential scanning calorimeter (DSC), transmission electron microscopy (TEM), mechanical properties and Vickers micro-hardness test methods. The results demonstrate that severe precipitation of θ(Al2Cu) and S(Al2CuMg) phase existed in the as-cast alloy, especially in the center position. Cu elements were concentrated at grain boundary and gradually decreased from the boundary to the interior. Numerous eutectic phases of θ(Al2Cu) and S (Al2CuMg) containing Zn and Ag elements were segregated at grain boundaries. The overheating temperature of the as-cast alloy is 497 °C. After two-stage homogenization treatment, the θ(Al2Cu) and S (Al2CuMg) in the surface, middle and center positions were completely dissolved into the matrix, thus achieved uniform homogenization effect. Moreover, water cooling could prevent the precipitation after homogenization, which provided good performance of the studied alloy. The optimum two-stage homogenization treatment of AA2060 alloy was 460 °C/4 h + 490 °C/2 4 h. The homogenization kinetic analysis was discussed as well. [ABSTRACT FROM AUTHOR]

Abstract Atom probe tomography was used to study the distribution of alloying elements near grain boundaries (GBs) in Zr-1.0Sn-0.3Nb-0.3Fe-(0.1Cu) alloys at the early stage of aging after β quenching. Cu was observed to segregate at GBs for the first time. Zr 3 Fe, Zr 3 (Fe,Cu) and Zr(Nb,Fe,Cr) 2 are precipitated on or near GBs. In addition, the impurity Si is mainly precipitates in the form of second-phase particles (SPPs), forming Zr 3 (Fe,Si) and Zr 3 (Fe,Cu,Si). [ABSTRACT FROM AUTHOR]

The recrystallization behavior of tantalum was investigated under two different annealing regimes, i.e. long-time annealing at low temperatures (LALT) and short-time annealing at high temperatures (SAHT), aiming to elucidate how annealing schedule arouses not only different texture evolution but grain shape as well. The texture and grain morphologies at each recrystallization stage were revealed by Electron Back-Scatter Diffraction (EBSD) technique. LALT was observed to enhance the {100} texture (〈100〉//ND (normal direction)) while simultaneously suppressing the {111} texture (〈111〉//ND); whereas a reverse trend of texture evolution was observed under SAHT. In terms of grain shape, different from the near-equiaxed grains introduced by LALT, SAHT resulted in lots of elongated grains with random orientations (i.e. orientations except for {111}〈uvw〉 and {100}〈uvw〉). The formation mechanism of elongated grains was established. It is anticipated that results in this study would provide guidelines for microstructural optimization of Ta sputtering targets. [ABSTRACT FROM AUTHOR]

Anisotropic Sb 2 Se 3 is an emerging earth-abundant photocathode for photoelectrochemical water splitting. However, controlling the growth of the Sb 2 Se 3 film with optimal [001] crystallographic orientation is still the most challenging issue. Here, we successfully synthesized [001]-oriented Sb 2 Se 3 via a reliable and facile method. The [001]-oriented Sb 2 Se 3 film could provide an excellent carrier-migration efficiency. Consequently, we achieved a record-high photocurrent density of -20.2 mA cm -2 at 0 V RHE and a very high half-cell solar-to-hydrogen efficiency of 1.36% under 1-sun simulated solar illumination in a TiO 2 /[001]-Sb 2 Se 3 photocathode. This work provides an effective strategy and important guidelines for rationally designing optoelectronic devices based on the [001]-oriented Sb 2 Se 3 film.