ld~lt~: "llaeeleetmniestmcturesofpureSeandY rnetals with hep structure have been determined by one-atom (OA) ~heory, which are [Ar](3d~)"~" (4s~)o'~°(4sf) °'~' and [Kr] (4d.)"~° (5s~)°'947° (Sst) °'~°° • According to their dectmnic structure, their potential cm'ves, cohesive energies, lattice constants, elasticity and the tempermawe dependence of linear thermal expansion coefficients have been calculated. The ehctnmie structures and characteristic properties of these meta/s wi& bcc stng4ures and primary liquids have also been studied, which has supplied the ~ parameters and property parameters of Sc and Y with diffet~mt crystal structures and also supplied a series of c~aplete data for the theoretical design of Sc and Y based materials.

The structure and composition of large-scale Al–Cu alloy ingots are inhomogeneous, and the segregation of (especially) elemental Cu negatively affects the uniformity and stability of the subsequent components. In this work, four ultrasonic generators were used to manipulate solidification/microstructures of cylindrical Al–Cu ingots (1250 mm in diameter; 3500 mm in length). The influence of ultrasonic configuration on both solidification microstructures and solute macrosegregation was investigated by changing the position parameters of generators for a fixed power. The results revealed that when the ultrasound is applied close to the center (I) from the 1/2 radius (II), the grain structure of the center undergoes significant refinement, degree of positive segregation in the center can be reduced, segregation index decreased from 0.2 to 0.15, and range of positive segregation in the center decreased from 200 to 150 mm. The segregation of elemental Cu was weakened by the combined effects of the ultrasound on the flow, heat transfer, and grain movement.

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Clinching technologies have better performance in joining different sheet materials. However, the protuberance and mechanical behaviors of clinched joints have always been needed to be improved. In this paper, a new clinching method, named two-strokes flattening clinching (TFC) process, was proposed to improve the mechanical behaviors of joints and flatten the protuberance. Mechanical testing including tension shearing tests were employed under quasi-static conditions to evaluate the different mechanical behaviors between TFC and conventional clinched joints. The influences of the different forming forces on mechanical response of these joints were studied. The static strength, energy absorption, material flow and failure modes of TFC and conventional clinched joints were investigated comparatively. The experimental results demonstrated that the tension-shear strength of TFC clinched joints was increased by 30.3% compared with conventional clinched joints at the forming force of 30 kN. Furthermore, the material flow analysis showed that the thickness and interlock of TFC clinched joints were increased by 79% and 45.9%, respectively. The energy absorption of TFC clinched joint was increased by 82%. In addition, the TFC process did not change the failure mode of clinched joints, and the failure mode of all clinched joints was neck fracture.