Advanced Materials Research Vols. 194-196

Abstract: The Mg-12Gd-2Y-0.5Sm-0.5Sb-0.5Zr alloy was prepared under flux protection. The morphology and crystal structure of β′ precipitate phases in aged alloy has been studied using transmission electron microscopy and X-ray diffraction. The orientation relationship between β′ precipitate and matrix could existed as [ 010]B_αB// [ 00]Bβ′B, (01 0) BαB// (020)B_β′B and (0001)B_αB was coherent with (001)B_β′B; [0001]B_αB// [001]B_β′B, (1 00)B_αB// (240)B_β′B and ( 010)B_αB was coherent with (0A^_,8EEA0)B_β′B. The HREM images indicated that the β' precipitates have a long-period ordered structure at the same time.

Abstract: The effects of different Sn or Se content on the corrosion behavior of lead-Sn or Pb-Sn_Se alloy in sulfuric acid solutions were investigated by metallurgical microscope, SEM, and weight loss tests. It was found that the addition Sn acts as grain coarser, but Se acts as grain refiner and Pb-Sn-Se alloys feature smaller grains. SEM for the corrosion layer indicated that the intergranular corrosion occurs on the surface of alloys with high Sn content (>1.wt%), but the general corrosion occurs on the surface of Pb-Sn alloys with low Sn content (<1.wt%) and all Pb-Sn-Se alloys. And The structure of corrosion layer and the eroded degree are relative to the height of the strap alloys above the plate. And the 1cm strap alloy above the plate was cathodically protected and almost no corrosion problems appeared. The corrosion rate of alloys containing Se is lower than Pb-Sn binary alloys. And the higher of Se content, the lower of corrosion rate. The results demonstrated that Pb-Sn-Se alloys show the potential for application as the negative strap in VRLA batteries.

Abstract: Displacement based seismic design of RC frame with friction damper is proposed in this paper based on the displacement shape of RC frame. and multi-degree-of-freedom system is transformed into an effective single-degree-of-freedom system. Based on equivalent linearization equivalent period is determined by using the elasto-plastic displacement response spectra, and then the structural members are designed. At the same time, target deformability of the frame and friction damper device is obtained by decomposing the structural storey drift. And the expected deformability of the structure can be guaranteed by appropriate the friction energy dissipation brace. This method could effectively control the seismic performance of the structure in earthquakes.

Abstract: Effect of Ca addition on the morphology modification in Mg-7Al-0.8Zn-0.2Mn-1Si (AS71) alloys has been investigated using X-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and various testing machines. The results show that when adding 0.1 wt% Ca, a small fraction of Mg₂Si change from Chinese script type to polygonal type; with the Ca addition up to 0.3 wt%, edges and angles of polygonal type Mg₂Si phase are changed; further increase in Ca addition, the morphology of Mg₂Si is changed to strip-like or spot-like one. Meanwhile, the addition of Ca results in the morphology of β- Mg₁₇Al₁₂ phase changing from discontinuous net-like to dispersive island-like. Ca exists as solid-soluting atomic in the matrix with small Ca addition while in the form of CaSi₂ with large Ca addition. Optimal mechanical properties can be achieved when Ca addition is 0.3 wt%.

Abstract: The microstructure and mechanical properties of aged Mg-5.5Al-1.2Y magnesium alloy with Sb addition are investigated by optical microscope, SEM and X-ray diffraction analyzer. The results show that with proper content of Sb addition,the microstructure of Mg-5.5Al-1.2Y magnesium alloy is refined obviously and high melting point intermetallic compounds Sb₃Y₅ and Mg₃Sb₂ are formed. Meanwhile, the β-Mg₁₇Al₁₂ phase is more distributed. With the increase of Sb addition, the mechanical properties of the alloy at room and elevated temperature increase at first, and then decrease. When the content of Sb is up to 0.5%, the values of tensile strength and elongation at room temperature, 150^ºC and 175^ºC are up to their maxima synchronously, 241MPa /16.84%, 198MPa/20.27.86% and 169MPa/21.21% respectively.

Abstract: By microstructure analysis and microhardness measuration, solid solution strengthening of Sm in Mg-10Y-1.5Sm alloy after solid solution and aging treatment was investigated. The results show that the microstructure of the alloy consists of α-Mg matrix and Mg₂₄Y₅ phase, and fine Mg₂₄Y₅ particles distribute in α-Mg matrix uniformly and dispersedly. No new phase forms after Sm addition, and Sm enhances α-Mg matrix and Mg₂₄Y₅ phase by solid solution effect. Compared with that of Mg-10Y alloy, the microhardness of the alloy with Sm addition increases obviously from HV87.7 to HV98.5.

Abstract: Taking Sn as the third element in the Al/Pb immiscible system, the Al-Sn-Pb layered composite materials at different temperatures were prepared by solid-liquid coating method. Microstructure of the layered composite materials was studied by scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS), and then the flexural strength and interface adhesion of the layered composite materials were measured. The results showed that, introducing of Sn reduced the enthalpy heat of mixing of Al/Pb system to be negative, and inter-diffusion of elements in the interface region occurred, and a metallurgical bonding interface between Pb and Al formed. The optimum diffusion-sintering temperature-time for the best flexural strength were determined by 250^οС , 0.5h, respectively. Under the controlled conditions, the mechanism was discussed.

Abstract: The response of electro-magneto-elastic long fiber composites containing periodically distributed reinforced phases under antiplane shear load coupled with inplane electromagnetic load is dealt with, there are three different electro-magneto-elastic materials in the unit cell (3-phase model), a rigorous analytical method is developed by using the generalized eigenstrain concept integrated with the doubly quasiperiodic Riemann boundary value problem theory. As an important application of the presented solution, the effective electro-magneto-elastic moduli are predicted and compared with the results from the generalized self-consistent method.

Abstract: A hybrid governing equation of the static response quantities and its sensitivity coefficients is derived for the composite laminated plates in the state space framework. Analytical and semi-analytical methods are given by using the trigonometric functions and B-spline wavelet on the interval (BSWI), respectively. Numerical results obtained by the semi-analytical methods are presented showing the effects of variation in the material properties of the plate on the displacement response quantities and their sensitivity coefficients. And the accuracy problem is also discussed by using these numerical results. Because of the use of the hybrid governing equation in the response analysis and sensitivity analysis, the convoluted algorithm is avoided in sensitivity analysis, and the response quantities and its sensitivity coefficients are obtained at the same time. The hybrid governing equation can also be easily modified to solve the sensitivity analysis problems of stiffened piezolaminated plates, or the plates and shells with piezoelectric patches or Fiber Metal Laminates.

Abstract: Meshless element of Hamilton canonical equation was established in this paper by combining the modified Hellinger-Reissner variational principle for elastic material and radial point interpolation functions. Using Multiquadric (MQ), Gaussian (EXP) and thin plane spine (TPS), the astringency of meshless methods and the effects of the dimensionless shape parameters on the maximum displacement were investigated by the numerical examples of the single or the cross-lay laminated plates. And all of the numerical results of displacement w were compared with that of MSC. Nastran This study introduced the advantages of meshless finite element method into semi-analytic solution of Hamilton canonical equation, and a new semi-analytic method was presented for Hamilton canonical equation.