摘要：The effects of parallel and angular butt designs with different gap widths on the microstructure and mechanical properties of the resultant magnesium joints in gas tungsten arc welding were investigated. The experimental results displayed that the tensile strength of the joint made with angular butt joint and 0.3 ram-wide gap reached 266 MPa, the joint fractured through the heat-affected zone or base metal during tensile testing, and the microstructure examination showed that no macropore appeared in the fusion zone. However, macropores in diameter of larger than 200 micron occurred for other joint designs, the tensile strength of the resultant joints decreased, and the joints fractured through the fusion zone during tensile testing. The fracture surfaces were examined by scanning electron microscopy and the microhardness distribution in the joints was measured by using a Vickers microhardness tester.

摘要：A battery concept based on the chemical system of magnesium (anode) and persulfate (cathode) is presented. A complete procedure is given to prepare the battery for testing, although no experimental data is presented herein. The similarities of this system to a well-tested Li||LiFePO4 system lend strong credibility to the concept, and the estimated performance characteristics presented. The advantages of this design include the following many areas. First, inexpensive, and available, battery reagents exist. Second, by analogy to the lithium ion battery for which comparisons are made, the full fabrication process for battery separator design is known and efficient;and both the kJ/kg and Amps/kg values are estimated to be substantially larger than the lithium ion battery (e.g., Li||LiFePO4) experimental design. Finally, flammability of the Mg||MgS2O8 system can be expected to provide less of a potential flammability concern, compared to comparable lithium ion batteries. This is because lithium metal, as with any alkali metal, is aggressively flammable even under reduced moisture environments. The proposed magnesium persulfate battery calculated metrics yield an improvement of 194% greater output power (W/cm2&middotkg), and 154% greater stored energy (MJ/kg) than state-of-the-art lithium iron phosphate batteries.

摘要：本文建立了一个真实时空的相场模型模拟,研究了含不同尺寸和体积分数的球形第二相颗粒的纳米结构AZ31镁合金的晶粒生长过程;第二相颗粒对单相合金系统晶粒组织演化和生长动力学的影响;并将模拟结果与微米晶结构镁合金的模拟结果相比较.通过在自由能密度函数的表达式中增加第二相颗粒的表达来改进模型.模拟结果表明:纳米晶组织中第二相粒子对晶粒长大的钉扎作用,与对微米晶组织下的作用有很大区别.纳米结构中,第二相颗粒对晶粒长大影响存在一个粒子尺寸的临界值,当第二相颗粒体积分数为10%时,粒子尺寸的临界值为200 nm,随粒子含量增加,临界尺寸值将减小.另一方面,粒子含量越大对晶界钉扎作用越大,晶粒平均尺寸越小.该研究将为选择复合加入和原位合成的方法在AZ31镁合金中引入第二相颗粒的实验研究提供显微组织设计的理论指导.