A magnesium alloy containing Al2Y particles was successfully fabricated by changing the content of Al in the Mg-6Y alloy melt. Its microstructure and mechanical properties were subsequently characterized. The results show that two types of Al2Y particles were discovered in the Mg-6Y-xAl (x = 0.5–5) alloys, which are namely the polygonal particles in the pre-precipitated phase and the discontinuous network of particles in the eutectic phase. With an increase in Al content, the amount of pre-precipitated Al2Y increases and the eutectic decreases gradually. When the Al content is 5 wt %, Al2Y particles are almost all in the pre-precipitated phase in the Mg-6Y alloy. After hot extrusion, the YA65 alloy could be regarded as the Mg master alloy that contains Al2Y particles with heterogeneous nucleation capability or Al2Y particle-reinforced magnesium matrix composites. The tensile strength of the as-extruded magnesium alloy is significantly improved at ambient temperatures.

ABSTRACT:A morphological study of hydroxypropyl cellulose (HPC) has been performed on solid films prepared by casting from a presheared liquid crystalline aqueous solution. Band textures were observed in a polarizing optical microscope. The sinusoidal supermolecular structure associated to the band texture was verified plausibly by comparison between the changes of experimental micrographs and theoretical birefringence patterns with the rotation of specimen. Some viewpoints in literature were commented. The pleated morphology was also confirmed in a scanning electron microscope.KEY WORDS Liquid Crystalline Polymer/ Band Texture/ Supermolecular Structure / Hydroxypropyl Cellulose / Polarized Optical Microscopy / Liquid crystalline polymer (LCP) exhibits distinct physical properties not to be expected in flexible polymers as well as in low molecular liquid crystals. One of interesting and puzzling phenomena is the band texture, which is common to all main chain LCP. The alternating dark and bright bands perpendicular to the preshearing direction was first observed in a polarizing microscope by Elliottt and Ambrose 1 from a solution cast film of poly(y-benyl-L-glutamate) (PBLG), which was long before LCP became of wide interest since the appearance of Kevlar, a famous highmodulus fiber. The band texture was then observed in the very Kevlar 2 and many other many chain LCPs. 3 -32 The bands are formed usually during shear relaxation, although occasionally, they can also be found during shear, 29 or during elongation relaxation, 27 or even without any noticeable macroscopic orientation. 26 A peculiar side chain LCP with mesogenic units attached directly in a sideon mode can also exhibit band texture in the sheared specimen. 33 Besides of interest in the light of the fundamental research, the 1132 band texture affects the mechanical properties of LCP materials very much 28 and, therefore, has attracted much attention of scientists and engineers.

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The moment behavior of beam-column connections should be considered in advanced steel space frame analysis. A trilinear model and calculation method were presented. Based on the comparison with the FEM results, it has been proved that the M-θ relationship of semi-rigid end-plate connections can be accurately estimated by this simplified calculation method and satisfy the requirement of structural design. This calculation method is simple and ease of use, it benefits application of this kind of joint in actual structure engineering and provides the basis and reference for design of the semi-rigid connection.