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In the present study, the microstructure and mechanical properties of a new Mg-4Al-3.5Ca-2Gd (AXE432) alloy are investigated. The microstructure of the as-cast AXE432 alloy consists of α-Mg, C14 (Mg2Ca), and C36((Mg, Al)2Ca) phases. After the heat treatment at 480 °C for 8 h, the C14 with fine lamellar structure changes from narrow stripes to micro-scale particles, and part of the C36 and the C14 dissolve into the α-Mg matrix, with many short needle-shaped C15 (Al2Ca) phase precipitating in the primary a-Mg grains. The AXE432 alloy extruded at a temperature as high as 420 °C exhibits a refined dynamically recrystallized (DRXed) microstructure with grain sizes less than 1.5 ± 0.5 μm and a strong {0001}<10 1 ¯ 0> basal texture with a maximum intensity of 5.62. A complex combination of the effects from grain size, texture, second-phase particles, and strain hardening results in balanced mechanical properties, with the tensile yield strength (TYS), ultimate tensile strength (UTS), elongation (El), compressive yield strength (CYS), and ultimate compressive strength (UCS) of 331.4 ± 2.1 MPa, 336.9 ± 3.8 MPa, 16.1 ± 2.3%, 270.4 ± 1.6 MPa and 574.5 ± 12.4 MPa, respectively. [ABSTRACT FROM AUTHOR]

The present study deals with the planktonic foraminiferal biostratigraphy of the Miocene–Pliocene sequence of three petroleum exploration wells (BY7-1-1, KP6-1-1 and KP9-1-1) in the Pearl River Mouth Basin (PRMB). In general, the three wells contain a fairly well-preserved, abundant foraminiferal fauna. The proposed planktonic foraminiferal zonation follows the scheme updated by Wade et al. (2011). Nineteen planktonic foraminiferal zones have been recognized, 14 zones (zones M1–M14) for the Miocene and 5 zones (zones PL1–PL5) for the Pliocene. The zonation is correlated with previously published biostratigraphic subdivisions of the Neogene succession in the PRMB and with international foraminiferal zonations. The zonal boundaries are mostly defined by the last appearance datum of zonal taxa of planktonic foraminifera, which is more reliable than the FAD (first appearance datum) events for ditch cutting sampling. Changes in the coiling of Globorotalia menardii (s. l.) are also used to define the zonal boundaries, where no LADs (last appearance datum) are available. The Fohsella fohsi group, comprising useful taxa for delimiting zonal boundaries of the middle Miocene in other areas, has a poor record within the Pearl River Mouth Basin due to unfavorable ecological conditions, and cannot be used for the studied wells. Different from the previously reported zonal scheme for the PRMB, the present zonation is based on correlation with the current standard planktonic foraminiferal zonation, with calibrated absolute ages.

The effects of Grp (graphite particles) addition and holding time on the microstructure and mechanical properties of the Grp/AZ91D composite were investigated in this work. The results indicated that the distribution of Grp in the matrix was determined by the self-stabilizing mechanism and relationships between the solidifying interface and the particles. Due to the self-stabilizing mechanism, a small amount of Grp would uniformly distribute in the melt alloy, and as the amount of Grp increased, agglomeration would occur. Accordingly, the former would be engulfed by the solidifying interface and the latter would be pushed. With an increased holding time, Grp tended to agglomerate, due to the interfacial reaction that occurred, and as a result, the solidifying interface will push it. The Grp/AZ91D composite with the addition of 1.5 wt.% Grp and a holding time of 15 min obtained grains 30.2 μm in size with a hardness of 89.07 HV, which was a decrease of 83.04% and increase of 35.06% compared to AZ91D, respectively. [ABSTRACT FROM AUTHOR]

The mechanical behaviors of the thixoforged in situ Mg2Sip/AM60B composite at elevated temperatures were evaluated. The results indicated that the thixoforged composite exhibits higher UTS (ultimate tensile strength) than that of the thixoforged AM60B at the cost of elongation. As the testing temperature rises from 25 to 300 °C, the UTS of both these two materials decreases while their elongations increases. The enhanced dislocation motion ability, the softened eutectic β phase at 120 °C, the activated non-basal slipping and the dynamic recovery and recrystallization mechanisms at 150 °C are responsible for the change in tensile properties with testing temperatures. The fracture mode transforms from the ductile into the brittle as the initial strain rate increases from 0.01 to 0.2 s-1 at 200 °C. [ABSTRACT FROM AUTHOR]

Presented an application of using 3D printing technique for the design and fabrication of a novel fiber Bragg grating (FBG) based sensing platform for foot planar pressure measurement. Pressure sensing unit was fabricated using 3D printing technique by layering of extruded polylactic acid (PLA) material and mounting FBG sensor at the center of each sensing unit for pressure measurement. Performance of the sensing system was validated by applying load step by step as well as cyclic load on FBG pressure sensors. A simulation study was carried out using the sensing platform to assess foot plantar pressure distribution arises from weight gaining and losing processes of pregnant woman. The monitored four different foot positions such as first metatarsus, second metatarsus, mid-foot and heel exhibited obvious differences during testing process. Foot plantar pressure of heel was 1.7 times of the pressure occurred at the first and second metatarsus (fore-foot) , while there was limited pressure occurred at the mid-foot position during weight gaining process of a female subject. The occurred pressures at the two metatarsus areas were around 90 % (pressure ratio) of heel and decreased continuously as the increase of subject weight, but weight losing process had very limited influence on this pressure ratio. Center of gravity of pregnant woman was found to shift backward substantially during the weighting gaining process, leading to a significant rise of the heel pressure. Hence, the protection of the heel position for female is highly important during both pregnancy and after baby delivery. [ABSTRACT FROM AUTHOR]