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Notes: The TEM observation was performed to investigate the precipitation hardening inMg-Gd-Zr alloy. Both the β’ and the β” phase coexist in the specimen aged at 473K for 16h. In thespecimen aged at 523K, the β’ phase which has base centered orthorhombic (bco) structure wasobserved at early stage during aging. The β’ phase has a globular shape and four atomic layerperiodicity in the [1100]Mg. The β’ phase grew with increasing aging time mainly along the [0001]Mgand the [1100]Mg

Notes: Precipitate microstructures in Mg-2.0Gd-1.2Y-0.75Zn-0.2Zr alloy were investigated andthe characteristic and mechanism of microstructure evolution in the alloy were discussed. Specificlong-period 14H ordered stacking structure was formed at grain boundary of Mg matrix crystals bysolution heat treatment at 773K and metastable β’ phase was formed during subsequent agingtreatment at 498K in the Zn-added Mg-Gd-Y alloys. These structure and phase exist simultaneously atthe peak-aged condition in the microstructure. Precipitate free zone (PFZ) of β’ phase does not exist atan interface between a 14H structure and Mg matrix inside the grain, however, PFZ exist near theedge of 14H structure at grain boundary. These results strongly suggest that high diffusion rate ofsolute atoms at grain boundary promotes the nucleation and growth of 14H structure

Notes: ZWK510 (Mg-5.0wt%Zn-0.9wt%Y-0.2wt%Zr) magnesium alloy containing Mg3YZn6 quasicrystal phase was prepared by conventional permanent mold casting. Part of the cast ingot was subjected to equal channel angular pressing (ECAP) directly; another part of the cast ingot was extruded initially, then ECAP was applied to the extruded alloy. After 4-pass ECAP, the fraction of coarse grains of the as-cast alloy was decreased to about 30%, and the grain size of fine grain was decreased to about 2 μm. Both strength and ductility of the as-cast ZWK510 alloy were significantly improved with increasing ECAP passes, which was resulted from broken and dispersed I-phase, and fine grains formed due to recrystallization. The as-extruded ZWK510 had an initial grain size of about 2 μm and bands of quasicrystal phase parallel to the extrusion direction. After the extruded alloy was subjected to ECAP, the grain size of the extruded alloy was further refined, the grain size was refined to below 0.5 um after 8-pass ECAP; and the quasicrystal phase was further broken and dispersed in the matrix. After ECAP, the elongation to failure of the extruded alloy was improved. However, both yield strength and ultimate tensile strength were decreased, which is considered to be resulted from the texture modification during ECAP

Notes: High resolution transmission electron microscopy（HRTEM）observation was performedto clarify morphology of precipitates at early stage of aging in Mg-Gd-Zr alloy. In the specimenaged at 423K, monolayer was observed on {1100}Mg planes. With increasing aging time, themonolayer and β” phase grew along the 〈1120〉Mg directions. Arrangement of bright dotscorresponding to {020}β’ except for the monolayer and β” phase was observed before peak agingstage. β’ phases formed at the same aging stage. Thus, these precipitates co-existed before peakaging stage. The monolayer, β” phase and β’ phase still co-existed in the peak aged specimen.The β’ phase was dominated in the peak hardness. It is revealed that the monolayer lying on{1100}Mg act as precursor of β” phase and β’ phase

Notes: An ultrafine-grained (UFG) Mg-5.0wt%Zn-0.9wt%Y-0.2wt%Zr magnesium alloy with agrain size of about 0.8 µm was produced by subjecting the extruded alloy to equal channel angularpressing (ECAP) for 8 passes at 473 K. Compressive testing was performed on the ECAPed alloy ina temperature range from 423 K to 523 K and under strain rates from 1.67×10-3 to 1.67×10-1 s-1. Theultrafine grains of the ECAPed alloy were stable during compression because of the presence of thedispersion of a fine quasicrystal I-phase and of precipitates in the alloy, which restricted graingrowth. The activation energy for the compression at the temperature range from 423 K to 523 K isclose to the value for grain boundary diffusion in magnesium, indicating that the compressivedeformation is mainly controlled by grain-boundary sliding

Notes: Equal channel angular pressing (ECAP) was applied to commercial pure magnesiumalloy, Mg-1wt%Si alloy and Mg-4.2wt%Zn-0.7wt%Y alloy. With increasing ECAP passes, bothtensile strength and ductility of the alloys are increased, which are mainly resulted from the grainrefinement. At the same time, for the Mg-Zn-Y alloy with inherent low damping capacity, dampingcapacity is increased after ECAP passes, however, the damping capacity is still low even after6-pass ECAP. While for the commercial pure magnesium and Mg-Si alloy with inherent highdamping capacity, although the damping capacity is decreased obviously after ECAP, Q-1 is stillgreater than 0.01. The damping capacity after ECAP processing is mainly influenced by grain sizeand deformation microstructure. ECAP paves a way for the development of magnesium alloys withhigh strength and high ductility combined with high damping capacity

Notes: The high resolution transmission electron microscope (HRTEM) observation wascarried out to investigate the microstructure of precipitates in Mg-Gd-Y-Zr alloy. In theearly stage of aging at 423K, monoatomic layers were observed along the (1 1 00)Mg plane.After 64h aging at 423K, the contrast of β” phase based on ordered D019 hexagonal superlattice structure was appeared. The monoatomic layers, two layers spaced by (1 1 00) Mgplanes and β’ phase based on bco-structure were observed in the specimen aged for 128h.In the peak- aged specimen, the β’ phase and monoatomic layers were observed

Notes: In Mg-Al-Zn and Mg-Al-Mn alloys containing 2.0~6.0mass%Al and 0~1.5mass%Zn,grain refinement in the as-rolled (F) specimens containing large amount of Al and Zn are achieved byboth dynamic recrystallization and dynamic precipitation during hot rolling and leads to high strengthand high ductility at room temperature. At high temperatures, the tensile strength of the investigatedalloys is almost the same, while the elongation of the F-specimens increases with increasing Al andZn contents, leading to 150% in Mg-4.5%Al-1.5%Zn alloy. High Al and Zn contents alloyssignificantly accumulate large working strain in grain interiors, and involve large amounts of highangle grain boundaries and fine spherical precipitates, which can become the nucleation sites forrecrystallization. Therefore, dynamic recrystallization in such alloys occurs at small strain regionduring tensile test. This dynamic recrystallization causes reduction of flow stress and large elongationby grain boundary sliding at high temperatures. Furthermore, .fine recrystallized grains contributes todeformation in normal direction, resulting in isotropic deformation behavior. Authors attempt toimprove proof stress and its anisotropic property of Mg-Al-Zn wrought alloys by grain size andprecipitates controls utilizing dynamic recrystallization and dynamic precipitation during hotextrusion. In the alloy specimens extruded at lower temperatures increasing Al and Zn contentsenhance dynamic recrystallization and dynamic precipitation, resulting in grain refinement and largeamount of Mg17Al12 precipitates. As a result, the extruded Mg-9%Al-1%Zn alloy specimen showshigh tensile strength of 370MPa, 0.2% tensile proof stress of 240MPa and moderate elongation of20%, which are almost same as standard values of tensile properties of T5-treated 6N01 Al extrudedalloy. Furthermore, a ratio of compressive proof stress to tensile proof stress of the as-extrudedspecimen improves up to a higher ratio of 0.9 than that of Mg-3%Al-1%Zn alloy specimen with noprecipitation, 0.5, due to prevention of tensile twin, which easily occurs during compressivedeformation even under a low applied stress perpendicular to the extrusion direction, by dynamicprecipitation of Mg17Al12 phase

Notes: In this study, it refined by the vacuum distilling refining and the billet was produced for the obtained 99.99% or more of purity magnesium deposit by compression forming, extrusion process was performed and the corrosion resistance of extrusions and the tensile characteristic which were acquired were investigated. The specimen showed good corrosion resistance rather than commercial AZ91D magnesium alloy die-castings. The specimen has high ductility and it is good, and compared with 99.9% of purity magnesium