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Three seaweed patterns, axial seaweed, titled seaweed, and degenerate seaweed were acquired from the various growth directions on the {111} planes of an Al-4.5% Cu single crystal. The inherently ordered crystal, with a seemingly disordered morphology, was investigated using back-reflection Laue (BRL) pattern and electron backscattered diffraction (EBSD). Microstructural characterization of the crystal indicated that the growth orientation of the seaweed could be linked to the crystallographic direction 〈011〉, having a favorable order. The formation of those three seaweed morphologies is sensitive to the anisotropy of the surface tension or interface stiffness caused by the six-fold symmetry of the crystal. Image, graphical abstract [ABSTRACT FROM AUTHOR]

A single crystal of Sb-doped Mg 2 Si 0.35 Sn 0.65 has been successfully prepared using high temperature-gradient directional solidification. The composition distribution of the crystal is uniform, and the preferred growth direction of the crystal is [111] orientation. The Seebeck coefficient ( S ) of the crystal is anisotropic in different orientations, and the electrical and thermal conductivity are isotropic properties. The S value in the [111] orientation can reach −265 μVK −1 , which is much larger than the reported results. Also, the power factor in the [111] orientation has a value of 5.56 mWm −1 K −2 , which leads to a maximum ZT of 1.3 at 730 K. Results of Hall testing and first principles calculations agree well with the experiment results. [ABSTRACT FROM AUTHOR]

Un-doped Mg 2 Sn single crystal has been revealed to be anisotropic in Seebeck coefficient at different orientations and possesses orientation-dependent conduction sign reversal (OCSR). At room temperature, the [111] orientation of the crystal shows the n-type conduction with a Seececk coefficient value of −265μVK −1 and the p-type conduction behavior in the [ 1 1 ¯ 0 ] and [ 11 2 ¯ ] orientations with 148μVK −1 and 115μVK −1 , respectively. First principle calculation on the anisotropic Seebeck coefficient of the crystal matches well with the experimental results, showing that the conducting effective mass plays an important role in determining the value of Seebeck coefficient. The single crystal Mg 2 Sn with the preferred [111] orientation is expected to have the best thermoelectric performance due to its large Seebeck coefficient value and the same electrical and thermal conductivities compared with other orientations of the crystal. [ABSTRACT FROM AUTHOR]

• Finding plate-like and hyperbranched seaweed in 3D conditions of metallic alloy. • Constructing a non-regular dendritic pattern selection map. • Well understanding effect of interface energy anisotropy on the dendritic pattern. Dendritic morphology and pattern selection are fundamentally important issues in solidification cycles. Here, a well-designed experiment was employed to investigate the solid–liquid interface energy anisotropy on the directionally solidified microstructures of Al-3 wt% Mg single crystals. Various dendritic morphologies, including regular dendrite, plate-like seaweed and hyperbranched seaweed, were found along the <100>, <110> and <111> orientations, respectively. The primary dendritic arm spacing (PDAS) of the seaweed pattern is closely related to the interface energy anisotropy and deviates from the current PDAS model. A non-regular dendritic pattern selection map is constructed to interpret the different dendrites occurring in alloy solidification. [ABSTRACT FROM AUTHOR]

The in-plane mechanical anisotropy of magnesium alloy sheet, which significantly influences the design of the parts produced by Mg alloy sheets, is of great importance regarding its wide application. Though the stress–strain response and texture evolution have been intensively investigated, and the anisotropy of Mg alloy can be significantly substantiated by its R-value, which reveals the lateral response of a material other than the primary response. As a consequence, the conjunction of viscoplastic self-consistent model and twinning and detwinning scheme (VPSC–TDT) is employed to investigate the in-plane anisotropy of magnesium alloy AZ31B-O sheet. The loading cases include both tension and compression along different paths with respect to the processing direction of the sheet. It is revealed that the stress–strain relation, texture evolution, R-value, and involved deformation mechanisms are all loading path-dependent. The unique R-values of Mg alloys are interpreted with the aid of modeling behaviors of Mg single crystals. The results agree well with the corresponding experiments. It is found that the hexagonal close-packed (HCP) crystallographic structure, deformation twinning, and initial basal texture are responsible for the characteristic behavior of Mg alloys. [ABSTRACT FROM AUTHOR]

In this study, the effects of solution treatment (ST) on the microstructure and anisotropic mechanical properties of Hastelloy X fabricated by laser directed energy deposition (L-DED) were investigated. The microstructure of the as-deposited (AD) sample presented coarse granular grains aligned with the deposition direction. Due to the segregation of Mo and Cr elements, a special cellular-structure was formed in the inter-dendritic region, along with the strip-like carbides consisting of both M 23 C 6 and M 6 C carbides. The cellular-structure homogenized rapidly after the ST. In detail, as the ST temperature increased, recrystallization generally occurred. Meanwhile, the strip carbides began to gradually dissolve and dissociate into dispersed particles which led to a drop in microhardness from 220 HV to 161 HV. The room temperature tensile results showed that the yield strength in the transversal direction (TD) and longitudinal direction (LD) decreased with the increase of ST temperature, reaching a minimum value of 285 MPa after the ST at 1175 °C. In addition, the ultimate tensile strength of the LD and TD samples reached maximum values of 693 MPa and 703 MPa at 1150 °C, respectively. It should be noted that the elongation of the low ductile TD sample can be improved significantly from 30% to 75% after the ST at 1175 °C. Therefore, it can be concluded that the anisotropy within the TD and LD samples can be effectively eliminated by controlling the cellular-structure, grain-structure, and carbide morphology during ST. • Cellular-structure is the major reason for anisotropic yield strength of as-deposited Hastelloy X. • Recrystallization during solution treatment could improve the anisotropic mechanical properties. • The dissolution of strip-like carbides benefits for enhancing the elongation of as-deposited Hastelloy X. [ABSTRACT FROM AUTHOR]