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The additions of alloying elements can significantly improve the mechanical properties of magnesium (Mg) alloys, mainly due to the fact that their additions change the critical shear stresses (CRSS) for dislocation slips. In this work, experimental and computational methods were used to explore the mechanisms responsible for the roles of Sm element addition in affecting the mechanical properties of Mg. The results showed that the addition of Sm obviously improves the microstructure and mechanical properties. It promotes the formation of twins and beneficially activated the non-basal slip at the initial stage of plastic deformation, resulting in a high ductility. The Visco-Plastic Self-Consistent (VPSC) and the two-beam diffraction results confirmed that the pyramidal slip and prismatic slip were activated during tensile testing. The quantitative analysis of slip traces verified that the volume of non-basal slips reached 35 % after Sm addition. The additions of Sm with solid solution increased the activities of pyramidal dislocation during deformation, which was beneficial to accommodate the c-axis strain, and finally improved the room temperature ductility of Mg. First-principle calculations demonstrate that the solute Sm atoms would reduce the stacking fault energy for basal and prismatic slips.

Mg–Al binary alloys in the concentration range from 0 to 4.0 wt.% Al have been prepared under conventional casting conditions. The as-cast Mg and Mg–Al alloys after solution treatment were processed via hot extrusion at 350 °C. The results show that Al has a positive influence on grain refinement and solution strengthening. The as-extruded Mg–Al alloys are fully recrystallized, and the tensile yield strength of the binary alloys is two times higher than that of pure Mg. Furthermore, the elongations of Mg–Al alloys are much higher than that of pure Mg. In addition, Mg and Mg–Al alloys were further studied by the viscoplastic self-consistent (VPSC) model to explore the activation and evolution of deformation modes. The simulation results match well with the experimental results.

Real-time accurate detection of three-dimensional (3D) objects is a fundamental necessity for self-driving vehicles. Most existing computer vision approaches are based on convolutional neural networks (CNNs). Although the CNN-based approaches can achieve high detection accuracy, their high energy consumption is a severe drawback. To resolve this problem, novel energy efficient approaches should be explored. Spiking neural network (SNN) is a promising candidate because it has orders-of-magnitude lower energy consumption than CNN. Unfortunately, the studying of SNN has been limited in small networks only. The application of SNN for large 3D object detection networks has remain largely open. In this paper, we integrate spiking convolutional neural network (SCNN) with temporal coding into the YOLOv2 architecture for real-time object detection. To take the advantage of spiking signals, we develop a novel data preprocessing layer that translates 3D point-cloud data into spike time data. We propose an analog circuit to implement the non-leaky integrate and fire neuron used in our SCNN, from which the energy consumption of each spike is estimated. Moreover, we present a method to calculate the network sparsity and the energy consumption of the overall network. Extensive experiments have been conducted based on the KITTI dataset, which show that the proposed network can reach competitive detection accuracy as existing approaches, yet with much lower average energy consumption. If implemented in dedicated hardware, our network could have a mean sparsity of 56.24% and extremely low total energy consumption of 0.247mJ only. Implemented in NVIDIA GTX 1080i GPU, we can achieve 35.7 fps frame rate, high enough for real-time object detection.

A novel sandwich grain structure of an Mg–Mn–Ce alloy was achieved by controlling the content of Mn in the traditional extrusion process. The solid-state Mn was dynamically precipitated during the extrusion. These finely precipitated particles hindered the grain boundary migration and refined the dynamically recrystallized grains. A sandwich-like grain structure was formed in as-extruded Mg–Mn–Ce alloys with Mn content increasing from 0.3 wt% to 0.9 wt%. This sandwich-like grain structure induced a tensile yield stress (TYS) that was improved from 86.5 MPa to 166.7 MPa; the Mg-0.9Mn-0.5Ce alloy exhibited improved yield isotropy. Here we discuss the formation mechanism for the sandwich-like grain structure and the strengthening mechanism in detail.

Fabricating bimodal grain structure is an effective way to improve the mechanical properties of Mg alloys. In present work, the various Mn contents (0, 0.5, 1.0, 1.5 wt%) are added in Mg-1.0Gd alloy to fabricate bimodal grain structure and improve the mechanical properties. After extrusion at 300 °C, bimodal grain structure is obtained in the Mg-1.0Gd-1.0Mn and Mg-1.0Gd-1.5Mn alloys. With the increment of Mn content, the average grain sizes of dynamic recrystallization (DRX) grains are refined from 8.6 to 1.2 μm. The mechanical properties are significantly improved. The Mg-1.0Gd-1.5Mn alloy exhibits the best tensile yield stress (TYS) and ultimate tensile stress (UTS), which is 280 MPa and 293 MPa. Comparing with the Mg-1.0Gd alloy, the improvement of TYS and UTS are 165 MPa (143%) and 98 MPa (51%). The enhancement of the strength is mainly attributed to the bimodal grain structure. The formation of the bimodal grain structure and the strengthening mechanisms are also discussed.

The effect of Mn on the microstructure and mechanical properties of as-extruded Mg-0.5Sr alloy were discussed in this work. The results showed that high Mn alloying (2 wt.%) could significantly improve the mechanical properties of the alloys, namely, the tensile and compressive yield strength. The grain size of as-extruded Mg-0.5Sr alloys significantly was refined from 2.78 &mu, m to 1.15 &mu, m due to the pinning effect by fine &alpha, Mn precipitates during the extrusion. Moreover, it also showed that the tensile yield strength and the compressive yield strength of Mg-0.5Sr-2Mn alloy were 32 and 40 percent age higher than those of Mg-0.5Sr alloy, respectively. Moreover, the strain hardening behaviors of the Mg-0.5Sr-2Mn alloy were discussed, which proved that a large number of small grains and texture have an important role in improving mechanical properties.

Developing high yield strength and ductility in low–cost Mg alloys using conventional plastic forming process is a tremendous challenge. Mg–Mn–based alloys have drawn considerable attention owing to their low–cost, high ductility and good corrosion resistance. However, the strength of Mg–Mn binary alloy is not satisfactory for industrial scale applications. In the present study, low content of Al alloying in Mg–1Mn alloy is the aim to obtain high strength and ductility of Mg–Mn–based alloys with low cost. Experimental results revealed that phase composition of the targeted Mg–1Mn–xAl (x = 0.3 wt%, 0.5 wt%, 1.0 wt%) alloys were composed of α-Mn + Al8Mn5, Al8Mn5 and Al8Mn5+Al11Mn4 phase, respectively. Al–Mn particles significantly refined the dynamically recrystallized (DRXed) grains. Among them, Al8Mn5 particles exhibited the most effective grain refinement. Therefore, Mg–1Mn–0.5Al alloy containing single-phase Al8Mn5 particles possessed the finest microstructure and exhibited the best mechanical properties. The high performance of the alloy was mainly attributed to the fine DRXed grains according to the Hall–Petch effect and to the large amount of fine Al8Mn5 particles through the dispersion strengthening. Meanwhile, the weak texture of fine grains enhanced the ductility. The fine DRXed grains and numerous Al8Mn5 particles effectively suppressed the extension twining, thus substantially enhanced the compression yield strength, and resulted in improved anisotropy.

Highly-uniform ultrafine Mg–3Al–1Zn alloy was successfully fabricated by a simple conventional extrusion method called continuous forging extrusion (CFE). After CFE, the average grain size of Mg–3Al–1Zn alloy was refined to 0.6 μm. The ultra-fine grain (UFG) AZ31 alloy exhibited an excellent combination of yield strength of 307 MPa and ductility of 26.3%. The improved mechanical properties were mainly attributed to grain boundary strengthening and texture weakening. The formation of dynamic recrystallized submicron grain in the CFE was also discussed.

Carbon-coated Co3O4 microparticles (Co3O4@C) with dendrite-like morphology are prepared by a low-temperature hydrothermal method and subsequent C2H2 chemical vapor deposition (CVD) for the first time. The synthesized precursor Co3O4 has a size of 8–10 μm, which is assembled by lots of aligned Co3O4 wire with 4–5 μm in length. After carbon coating, Co3O4 microparticles were proved to be coated in amorphous carbon of ~10 nm. A plausible formation process of the dendrite-like Co3O4 and Co3O4@C is proposed based on the morphology and structure characterizations of the materials. As an anode material for lithium-ion batteries, the Co3O4@C composite electrode exhibits higher reversible capacity and better cycling performance than the unmodified Co3O4 electrode. The reversible capacity of the Co3O4@C composite after 40 cycles is 500 mAh g−1, much higher than that of Co3O4 (148 mAh g−1). Electrochemical impedance spectra and cyclic voltammogram indicate that the carbon layer coated on Co3O4 by CVD can improve the electrochemical activity and enhance the reversibility of Co3O4 during charge/discharge cycles.