Mechanical properties and microstructure of as-cast and extruded Mg-（Ce, Nd）-Zn-Zr alloys

1INTRODUCTION Thebeneficialinfluenceofrareearth(RE)metalsontheambientandelevatedtemperature mechanicalpropertiesofmagnesiumalloyhaslongbeenrecognized[13].Recently,Yttriumisaddedto Magnesiumalloytoimproveitstensilestrength andcreepresistance,andsuchinvestigationsatheat resistantmagnesiumalloyhaveledtothede velopmentofWE43andWE54alloys[4,5].Al thoughsuchalloysexhibitgoodpropertiesupto573Kthroughcastingandextruding,therelativelyhighcostofYttriumrestrictstheapplicationof suchalloys.Otherr…     

Degradation behaviors,thermostability and mechanical properties of poly （ethylene terephthalate）/polylactic acid blends

It is difficult for polyethylene terephthalate （PET） to degrade,which caused severe pollution.In this work,polylactic acid （PLA） was introduced to improve the degradation of PET.PET/PLA was synthesized by extrusion blending.The thermal,crystalline and mechanical properties of blends were investigated with TGA,DSC,WAXD and universal testing machine.The degradation of the blends in soil,acid and alkaline buffer solutions was assessed,respectively.It was found that the introduction of a little PLA promoted crystallization of PET during injection molding process.The starting decomposition temperature lowered from 412.1 ℃ of pure PET to 330.4 ℃ at 50% PLA content,tensile and bending strength of blends gradually decreased with the PLA content increasing,while the degradation rate improved.Alkaline environment was most beneficial for blends to degrade.The degradation mechanism was discussed.     

Effects of Al and Sn on electrochemical properties of Mg-6%Al-1%Sn （mass fraction） magnesium alloy as anode in 3.5%NaCl solution

Mg-6%Al-1%Sn（mass fraction） alloy is a newly developed anode material for seawater activated batteries. The electrochemical properties of Mg-1%Sn, Mg-6%Al and Mg-6%Al-1%Sn alloys are measured by galvanostatic and potentiodynamic tests. Scanning electron microscopy（SEM） with energy dispersive spectrometry（EDS） is used to characterize the microstructures of the experimental alloys. The results show that the Mg-6%Al-1%Sn alloy obtains more negative discharge potential（-1.38 V（vs SCE）） in hot-rolled condition. This is attributed to the fine dynamically recrystallized grains during the hot rolling process. After the experimental alloys are annealed at 473 K for 1 h, the discharge potentials of Mg-6%Al-1%Sn alloy are more negative than those of Mg-6%Al alloy under different current densities. After annealing at 673 K, the discharge potentials of Mg-6%Al-1%Sn alloy become more positive than those of Mg-6%Al alloy. Such phenomenon is due to the coarse grains and the second phase Mg2 Sn. The discharge potentials of Mg-1%Sn shift positively obviously in the discharge process compared with Mg-6%Al-1%Sn alloy. This is due to the corrosion products pasting on the discharge surface, which leads to anode polarization.     

Microstructure, crystalline phase and electrical properties of Li0.06（Na0.5K0.5）0.94Nb（1-2x/5）MgxO3 lead-free piezoelectric ceramics

MgO-modified Li0.06(Na0.5K0.5)0.94NbO3(L6NKN) lead-free piezoelectric ceramics were synthesized by normal sintering at a relatively low temperature of 1000°C.The crystalline phase,microstructure,and electrical properties of the ceramics were investigated with a special emphasis on the influence of MgO content.The addition of MgO effectively improves the sinterability of the L6NKN ceramics.X-ray diffraction analysis indicates that the morphotropic phase boundary(MPB) separating orthorhombic and tetragonal ph...     

Hydriding and dehydriding kinetics of nanocrystalline and amorphous MgzNi1-xMnx （x=0-0.4） alloys prepared by melt spinning

A partial substitution of Ni by Mn was implemented in order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloys.The nanocrystalline and amorphous Mg2Ni-type Mg2Ni1-xMnx(x=0,0.1,0.2,0.3,0.4) alloys were synthesized by the melt-spinning technique.The structures of the as-cast and spun alloys were studied by X-ray diffractometry(XRD),scanning electron microscopy(SEM) and high resolution transmission electron microscopy(HRTEM).The hydrogen absorption and desorption kinetics of the alloys ...     

Structure and Mixed Electronic-ionic Conducting Properties of La0.6Sr0.4Co1-yFeyO3（y= 0-1.0） Ceramics Made by a Citrate Method

La0.6Sr0.4Co1-yFeyO3（y= 0-1.0） powders were synthesized by a citrate method, and the structure and mixed electronic-ionic conducting properties of the resulting ceramics were investigated. The synthesized La0.6Sr0.4Co1-yFeyO3 powders have a pure perovskite structure and consist of uniform and fine particles. A perovskite struciure with rhombohedral symmetry was certified for the La0.6Sr0.4Co1-yFeyO3 ceramics. The increase of Co/Fe ratio significantly promoted the grain growth and microstructural densification. The La0.6Sr0.4Co1-yFeyO3 compositions with relatively higher Co/Fe ratio exhibit superior mixed conducting properties. The electronic structure and microstructure of the ceramics are responsible for the variation of the mixed conducting properties with Co/Fe ratio.