先进大学文化与大学良性发展论纲

理解大学文化的内涵,其基本内容应涵盖大学的精神文化、制度文化、物质文化三个层次.     

La替代Mg对Mg2Ni型合金电化学贮氢性能的影响

用快淬工艺制备了纳米晶和非晶Mg2Ni型Mg2 -xLaxNi (x=0,0.2,0.4,0.6)贮氢电极合金,获得长度连续,厚度约为30μm,宽度约为25 mm的薄带.用XRD、SEM和HRTEM分析了快淬合金薄带的微观结构,测试了合金薄带的电化学性能及电化学交流阻抗谱(EIS).快淬无La合金具有典型的纳米晶结构,...     

Influences of stoichiometric ratio B/A on structures and electrochemical behaviors of Lao.75Mg0.25Ni3.5Mx （M=Ni,Co; x=0-0.6） hydrogen storage alloys

In order to investigate the influences of the stoichiometric ratio ofB/A （A： gross A-site elements, B： gross B-site elements） and the substitution of Co for Ni on the structures and electrochemical performances of the AB3.5-4.1-type electrode alloys, the La-Mg-Ni-Co system La0.75Mg0.25Ni3.5Mx （M=Ni, Co; x= 0, 0.2, 0.4, 0.6） alloys were prepared by induction melting in a helium atmosphere. The structures and electrochemical performances of the alloys were systemically measured. The results show that the structures and electrochemical performances of the alloys are closely relevant to the B/A ratio. All the alloys exhibit a multiphase structure, including two major phases, （La, Mg）2Ni7 and LaNis, and a residual phase LaNi2, and with rising ratio B/A, the （La,Mg）2Ni7 phase decreases and the LaNi5 phase increases significantly. When ratio B/A-3.7, the alloys obtain the maximum discharge capacities. The high rate discharge（HRD） capability of the alloy （M=Ni） monotonously rises with growing B/A ratio, but that of the alloy （M=Co） first mounts up then declines. The cycle stability of the alloy （M-Co） monotonously increases with rising B/A ratio, but it first decreases slightly then increases for the alloy （M=Ni）. The discharge potential of the alloy （M=Ni） declines with increasing B/A ratio （x〉0.2）, but for the alloy （M-Co）, the result is contrary. The substitution of Co for Ni significantly ameliorates the electrochemical performances. For a fixed ratio B/A=3.7, the Co substitution enhances the discharge capacity from 365.7 to 401.8 mA.h/g, the capacity retention ratio （S100） after 100 charging-discharging cycles from 50.32% to 53.26% and the HRD from 88.65% to 90.69%.     

Structures and electrochemical performances of La_(0.75-x)Zr_xMg_(0.25)Ni_(3.2)Co_(0.2)Al_(0.1) (x=0-0.2) electrode alloys prepared by melt spinning

The La-Mg-Ni system A2B7-type electrode alloys with nominal composition La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1(x=0,0.05, 0.1,0.15,0.2)were prepared by casting and melt-spinning.The influences of melt spinning on the electrochemical performances as well as the structures of the alloys were investigated.The results obtained by XRD,SEM and TEM show that the as-cast and spun alloys have a multiphase structure,consisting of two main phases(La,Mg)Ni3 and LaNi5 as well as a residual phase LaNi2.The melt spinning leads to an obvious increase of the LaNi5 phase and a decrease of the(La,Mg)Ni3 phase in the alloys.The results of the electrochemical measurement indicate that the discharge capacity of the alloys(x≤0.1)first increases and then decreases with the increase of spinning rate,whereas for x0.1,the discharge capacity of the alloys monotonously falls.The melt spinning slightly impairs the activation capability of the alloys,but it significantly enhances the cycle stability of the alloys.     

Co替代Ni对快淬纳米晶/非晶Mg_2Ni型合金吸放氢动力学的影响

为了改善Mg2Ni型合金的吸放氢动力学性能,用Co部分替代合金中的Ni。用快淬工艺制备了纳米晶和非晶Mg20Ni10-xCox(x=0,1,2,3,4)贮氢合金,分析了铸态及快淬态合金的微观结构,测试了合金的吸放氢动力学性能。研究了Co替代Ni及快淬工艺对合金吸放氢动力学性能的影响。结果表明,在快淬合金(x=0)中没有发现非晶相,但快淬合金(x=4)显示了纳米晶/非晶结构,表明Co替代Ni提高了Mg2Ni型合金的非晶形成能力。Co替代Ni不改变合金的Mg2Ni主相,但形成了第二相MgCo2。随Co替代量的增加,合金的吸氢量先增加而后减少,但其放氢量随Co替代量的增加而单调增加。     

非晶态合金在电磁屏蔽领域中的应用现状

非晶态合金是性能优异的软磁材料,在电磁屏蔽领域获得了良好的应用效果。本文在介绍电磁屏蔽机理的基础上,对非晶态合金作为电磁屏蔽材料在国内外的研究和应用情况进行了综述,并对今后的应用前景进行了展望。     

快淬无钴AB5型贮氢合金研究进展

本文主要阐述了无钴稀土系AB5型贮氢合金研究现状,介绍了通过真空快淬技术及成分设计来改善其微观结构,从而提高AB5型贮氢合金的综合电化学性能的方法.并根据目前发展现状指出了无钴稀士系AB5型贮氢合金未来研究方向.     

熔体快淬对纳米晶和非晶Mg20Ni10-xCox(x≈0～4)合金电化学贮氢性能的影响

为了改善Mg2Ni型合金的电化学贮氢性能,用Co部分替代合金中的Ni.用快淬工艺制备了纳米晶和非晶Mg20Ni10-xCox(x=0、1、2、3、4)贮氢合金,分析了铸态及快淬态合金的微观结构,测试了合金的电化学贮氢性能.研究了Co替代Ni及快淬工艺对合金电化学贮氢性能的影响.结果表明,Co替代Ni不改变合金的Mg2Ni主相,但形成了第二相MgCo2.在快淬(x=0)合金中没有发现非晶相,但快淬(x=4)合金显示了纳米晶、非晶结构,表明Co替代Ni提高了Mg2Ni型舍金的非晶形成能力.熔体快淬显著的改善了合金的电化学贮氢性能,合金放电容量和电化学循环稳定性均随淬速的增加而增加.     

模拟纤维增强复合材料的相似子域边界元法

根据夹杂相积分区域的相似性,提出了相似子域边界元法求解方案。把含随机分布夹杂相的固体归结为对一个含有内边界条件复连通域问题的求解,与传统的有限元和边界元分域解法相比,显著地提高了计算效率。应用相似子域边界元法,对含有随机分布圆形和椭圆形夹杂相的固体材料进行了大量数值计算,并把夹杂相与基体材料之间从理想粘结扩展到带有界面层的情况。这些计算为相应纤维增强复合材料宏观等效力学特性研究提供了有效的数值模拟方法。      

微合金化钢的动态再结晶及其显微组织的研究

应用Ｇｌｅｅｂｌｅ－１５００热模拟试验机测定了合金化钢在不轧温度下的真应力－真应变曲线,研究了终轧温度及微合金元素含量对动态再结晶的影响。研究结果表明,Ｖ、Ｎｂ可显著抑制微合金化钢轧制过程中形变奥氏体的动态再结晶,因此,在较高的终轧温度下,仍能得到细小而均匀的显微组织。