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The current research of Charpy impact mainly focuses on obtaining the ductile brittle transition temperature of materials by experiments. Compared with experiments, numerical simulation can study many problems with harsh conditions. However, there are still few studies on the influence of geometric factors such as side grooves. In this paper, the geometry of standard Charpy impact test is designed. Specimens with different widths and side grooves are tested. The finite element model of Charpy impact was established by ABAQUS software. Use test results and simulation results to verify each other. The effects of sample width, side groove depth and side groove bottom fillet on the impact fracture resistance of the sample were studied. The results show that the specimen width is positively correlated with the impact toughness of the specimen. The side groove greatly reduces the impact toughness of the material; the toughness of side groove decreases with the increase of depth; the fracture toughness of side groove decreases with the increase of fillet at the bottom of side groove. The proportion of toughness energy to impact energy of samples was analyzed. The results show that the toughness energy accounts for about 70% of the impact energy of the sample, which has little to do with the geometric characteristics of the sample. This study presents a reliable method for studying Charpy impact tests. The influence of geometric parameters is obtained, which provides a reference method for the study of impact toughness of high toughness materials. [ABSTRACT FROM AUTHOR]

Corona textures, characterized by specific mineral assemblages as layers between existing phases, are frequently observed in high-grade metamorphic rocks. The mechanisms of corona formation have been extensively investigated, however direct dating of corona phases has rarely to be attempted. In order to decipher the timing and duration of corona formation and its implications for metamorphic processes, an integrated garnet Lu–Hf and Sm–Nd and zircon U–Pb petrochronological study was conducted on a corona-bearing granulite from the Miyun region in the North China Craton. The Miyun region, located at the joint area of the Archean Eastern Block and the Paleoproterozoic Trans-North China Orogen, offers a distinctive opportunity to study polymetamorphic processes within the North China Craton. The sample shows a corona texture, primarily composed of garnet, minor clinopyroxene and quartz, that formed at the boundary between plagioclase and orthopyroxene. Pseudosection modelling for the effective bulk composition of reactive domains and conventional thermobarometric calculations indicate that the anhydrous corona assemblage (comprising clinopyroxene, garnet and quartz) formed at ~ 0.9 GPa and ~ 740 ℃. The subsequent hydrous retrogression took place at ~ 0.5 GPa and ~ 670 ℃ and led to the growth of amphibole and biotite. A Lu–Hf garnet date of 1864 ± 3 Ma is significantly younger than the U–Pb date of ca. 2454 Ma for metamorphic zircons in the sample, consistent with the disequilibrium partitioning of rare earth elements between the two phases. The well-preserved Lu zoning in garnet supports the interpretation that the Lu–Hf date represents the age of garnet growth and approximates the timing of formation of the anhydrous corona assemblage. Thus, the U–Pb age reflects a distinct Archean metamorphic event that has been widely documented in high-grade rocks across the Eastern Block of the North China Craton. The garnet Sm–Nd date of 1817 ± 6 Ma is indistinguishable from an amphibole-biotite Lu–Hf date of 1819 ± 16 Ma and ~ 47 Myr younger than the corresponding garnet Lu–Hf date. The younger Sm–Nd age represents the timing of cooling and post-dates retrogression. The Paleoproterozoic and Archean ages in the Miyun granulite align with the major tectonic events in the Trans-North China Orogen and the Eastern Block, respectively. This consistency suggests that the Miyun region likely experienced concurrent metamorphic events in both the Trans-North China Orogen and the Eastern Block. This texture-based Lu–Hf and Sm–Nd dating approach has wide applicability for rocks with explicit textures, facilitating precise extraction of temporal intervals in the metamorphic process. [ABSTRACT FROM AUTHOR]

Microstructure and mechanical properties of extruded Mg-7Sn-5Zn-xAl (x = 0, 1, 2 and 3 wt.%) alloy were investigated. The as-cast Mg-7Sn-5Zn alloy mainly comprised α-Mg dendrites, Mg2Sn and nanosized Mg-Zn phases in a Mg matrix, whereas the quasicrystal (icosahedral (I)) phase precipitated with the addition of Al. After extrusion, the grain size decreased due to dynamic recrystallization and the resulting particles were crushed and distributed along the extrusion direction. The highest tensile strength was exhibited by the extruded Mg-7Sn-5Zn-2Al alloy, which had a yield strength, ultimate tensile strength and elongation to failure of 198, 343 MPa and 18.7%, respectively. The high tensile strength was mainly attributed to grain refinement and precipitation strengthening of the Mg2Sn and icosahedral phases. [ABSTRACT FROM AUTHOR]