Renguo SONG
材料科学技术（英）
Nafion/polypyrrole and Nafion/Dimethysulfoxid (DMSO) organic coatings were prepared on the surface of pure magnesium by simple immersion and heat treatment. The morphologies and corrosion resistance of the organic coatings were investigated by using optical microscopy and electrochemical corrosion testing, respectively. It is shown that Nafion/polypyrrole organic coatings resulted in the corrosion resistance of magnesium decreasing; while Nafion/DMSO organic coatings can effectively improve the corrosion resistance of magnesium. Also, the corrosion resistance increased with the thickness of the Nafion/DMSO organic coating increased.
关键词:
Magnesium
,
Nafion/polypyrrole
,
organic
,
coa
Fang Geng
材料科学技术（英）
Three-dimensional honeycomb-structured magnesium (Mg) scaffolds with interconnected pores of accurately
controlled pore size and porosity were fabricated by laser perforation technique. Biodegradable and bioactive β-
tricalcium phosphate (β-TCP) coatings were prepared on the porous Mg to further improve its biocompatibility,
and the biodegradation mechanism was simply evaluated in vitro. It was found that the mechanical properties
of this type of porous Mg significantly depended on its porosity. Elastic modulus and compressive strength
similar to human bones could be obtained for the porous Mg with porosity of 42.6%-51%. It was observed
that the human osteosarcoma cells (UMR106) were well adhered and proliferated on the surface of the β-
TCP coated porous Mg, which indicates that the β-TCP coated porous Mg is promising to be a bone tissue
engineering scaffold material.
关键词:
Magnesium
,
Bone tissue engineering
,
β-TCP coating
,
Biocompatibility
Donghong Zhang
材料科学技术（英）
The development of texture during plastic deformation plays an important role in determining the stretch formability of magnesium alloy sheets. In this study, the orientation stability during equibiaxial tension of magnesium was analyzed based on three dimensional lattice rotations calculated by using a rate-dependent crystal plasticity model and assuming five different combinations of slip modes. The results show that no orientations can satisfy the stability criteria with both zero rotation velocity and convergent orientation flow in all dimensions. However, relatively stable orientations with zero rotation velocity and an overall convergence are found. They are featured by characteristic alignments of specific crystallographic directions in the macroscopic axis of contraction, depending on the slip modes involved in the deformation. It is also shown that the orientation stability varies significantly with the deviation of deformation mode from equibiaxial tension. The simulation results are briefly discussed in comparison with pre-existing experiments.
关键词:
Magnesium
Yanjin LU
,
Lili TAN
,
Hongliang XIANG
,
Bingchun ZHANG
,
Ke YANG
金属学报(英文版)
A composite coating was fabricated on pure magnesium by hydrothermal treatment in order to reduce its degradation in body environment. The coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The XRD pattern showed that the main composition of the coating was a mixture of CaSiO3, MgSiO3 and Mg(OH)2. Electrochemical test showed that the corrosion current density (emcorr) of the coated magnesium was decreased by about two orders of magnitude compared with that of the bare magnesium, and the EIS measurement also showed that the corrosion resistant performance of the coated magnesium was significantly enhanced. Meanwhile, weight loss test showed that the weight loss of the coated magnesium was lower than that of the bare magnesium. Hence, the present study indicated that the composite coating could greatly slow down the degradation of pure magnesium.
关键词:
Magnesium
,
null
,
null
,
null
,
null
Sangwon Lee
,
Bonggyu Park
,
Yongho Park
,
Ikmin Park
材料科学技术（英）
The effect of Sn addition on the microstructures and mechanical properties of Mg-5Al-2Si alloys was investigated with variations of Sn contents (3 and 6 wt pct). The microstructure of the alloy was characterized by the presence of Mg2Sn particles within matrix and at grain boundaries. As the Sn contents increased, yield and ultimate tensile strength were increased at room temperatures and 150℃. Creep properties were improved with the increasing amount of Sn due to the fine precipitation of Mg2Sn phases within grain during creep.
关键词:
Magnesium
,
null
,
null
,
null
J.M.Kim
,
J.H.Jun
,
W.J.Jung
材料科学技术（英）
Mechanical properties of Mg-Al based alloys at different fabrication state, namely as-cast, hot rolled, and annealed, were investigated to develop the alloys that are suitable for the casting/hot working process. Experimental results indicated that the castability such as hot cracking resistance tends to improve with increasing the aluminum content. However, the elongation at elevated temperatures was observed to decrease as the Al content increases, implying difficulties in hot forming. A small amount of Zr additions could significantly enhance the room temperature mechanical properties of hot-rolled Mg-6%Al-1%Zn alloy. The tendency of remarkable grain coarsening at high temperatures was effectively reduced by the Zr additions. TEM analyses suggested that very fine Al3Zr precipitates formed in the Zr-added alloy are responsible for the obtained results.
关键词:
Magnesium
,
null
,
null
,
null
Guangli Bi
材料科学技术（英）
Microstructure and mechanical properties of an extruded Mg-2Dy-0.5Zn (at.%) alloy during isothermal ageing at 180 °C were investigated. Microstructure of the as-extruded alloy is mainly composed of α-Mg phase, 14H long period stacking order (LPSO) phase and small amounts of (Mg, Zn)xDy particle phases. During ageing, the 14H LPSO phase forms and develops and its volume fraction increases with increasing ageing time. Tensile test showed that the peak-aged alloy exhibits similar yield and ultimate tensile strengths and elongation to failure at room temperature, 100 °C and 200 °C, but excellent elevated temperature strengths at 300 °C as compared to the as-extruded and over-aged alloys. The analysis showed that the excellent elevated temperature strengths of the peak-aged alloy are attributed to the LPSO phase strengthening and the grain refinement strengthening, and the role of the LPSO strengthening is related to not only its amount, but also its morphology.
关键词:
Magnesium
Donghong Zhang Saiyi Li
材料科学技术（英）
The development of texture during plastic deformation plays an important role in determining the stretch formability of magnesium alloy sheets. In this study, the orientation stability during equibiaxial tension of magnesium was analyzed based on three dimensional lattice rotations calculated by using a rate-dependent crystal plasticity model and assuming five different combinations of slip modes. The results show that no orientations can satisfy the stability criteria with both zero rotation velocity and convergent orientation flow in all dimensions. However, relatively stable orientations with zero rotation velocity and an overall convergence are found. They are featured by characteristic alignments of specific crystallographic directions in the macroscopic axis of contraction, depending on the slip modes involved in the deformation. It is also shown that the orientation stability varies significantly with the deviation of deformation mode from equibiaxial tension. The simulation results are briefly discussed in comparison with pre-existing experiments.
关键词:
Magnesium
Yanjin Lu
材料科学技术（英）
A biodegradable Ca-P coating mainly consisting of β-tricalcium phosphate (β-TCP) was fabricated on pure magnesium via the chemical deposition in a simulated Hank0s solution. The method significantly accelerated the coating formation on magnesium. Moreover, the morphology, phase/chemical composition, the coating formation mechanism as well as degradation behavior in phosphate buffered saline (PBS) solution were investigated. Scanning electron microscopy (SEM) images showed that the coating had three layers and X-ray diffraction (XRD) patterns showed that the coating mainly contained Ca3(PO4)2 and (Ca,Mg)3(PO4)2. Electrochemical test showed that the corrosion current density (Icorr) of the coated Mg was decreased by about
one order of magnitude as compared to that of pure magnesium. The immersion test indicated that the coating could obviously reduce the degradation rate.
关键词:
Magnesium
Ping YANG
金属学报(英文版)
Experiments show that special processing techniques such as asymmetrical rolling (ASR), equal channel angular pressing (ECAP) and equal channel angular rolling (ECAR) can weaken the basal texture of the magnesium alloys and therefore improve their plasticity. However, the deformation mechanisms related are different. In this paper, we determine the deformation mechanisms activated during ASR, ECAP and ECAR by calculation of orientation factors. Analysis shows that during ASR the shear stress σ13 on the rolling plane of the samples obviously weakens the basal slip and tension twinning that all produce basal texture and improve plasticity due to the promotion of tilt basal texture. During ECAP the shear stress σs on the intersecting plane of two channels promotes tension twinning in the basal
oriented grains, whereas under ECAR the shear stress σ13 induced by roller friction on the rolling plane produces the shear stress σs on the intersection plane of the two channels that also promotes tension twinning. Although the shear strain is lower in ECAR than in ECAP, the channel clearance in ECAR facilitates tension twinning.
关键词:
Magnesium
,
asymmetrical rolling
,
equal channel angular pressing
,
equal channel angular rolling
,
deformation
