Changes in the potential energy upon the formation of vacancies in the volume and in the cores of crystallite-conjugation regions in cubic polycrystalline metals

Changes in the potential energy of atoms that constitute the nearest neighborhood of vacancies formed in the bulk of d transition and precious cubic metals have been determined. These changes agree with the available first-principles calculations of changes in the potential energy of atoms of the nearest neighborhood of vacancies. In the cores of crystallite-conjugation regions (CCRs) of bcc polycrystalline d transition metals, the formation of vacancies is accompanied by positive changes in the potential energy of atoms of their nearest neighborhood. The absolute magnitudes of these changes are several times less than the changes in the potential energy of atoms of the nearest neighborhood of vacancies in the bulk of these metals, in accordance with the relationship between the enthalpies of formation of vacancies in these regions of polycrystals. The changes in the potential energy of atoms of the nearest neighborhood of vacancies formed in the cores of CCRs of fcc polycrystalline metals are negative because of the split structure of vacancies in the CCR cores of such metals.     

美国大学终身教职制形成要素的历史分析

终身教职制度是美国大学的主流聘任制度,虽然在二十世纪九十年代之后它遭遇改革,但美国主要大学,特别是研究型大学仍为教师提供终身教职。本文从历史角度分析了终身聘任制度的形成要素：教师参与同行的聘任、试用期、“非升即走”、正式地位获得之后解聘的充分理由与正当程序;认为终身教职制度之所以成为美国大学的主流聘任制度是它汲取了大学聘任实践中最合理的要素。     

热核聚变反应堆关键结构件的连接技术进展

综述了热核聚变反应堆关键结构件－－面向等离子元件在连接方法、工艺及机理方面的现状，分析了存在的问题，并对今后的研究进行了展望。     

HPLC in the study of radiation-chemical changes in the composition of wines

The study of radioprotective properties of wine related to their ability to regulate redox processes and resist oxidative stress caused by exposure to ionizing radiation and other factors in living systems is of current interest. Physico-chemical approach, including the use of such methods as chromatography for research on the effect of these factors is underdeveloped. In this paper, the HPLC method was used to identify products of γ-radiolysis of serotonin and other phenolic components of wines and calculate the degrees of conversion of the starting compounds. These data are necessary for measuring the radiation resistance of biologically active compounds, including serotonin, since recently the radiation-chemical methods of sterilization of medicinal preparations on their basis are widely used. Determination of products of radiation-chemical reactions of bioactive compounds is important in the problem of studying the mechanism of the redox reactions in biological systems with different degrees of organization.     

封口墙板裂纹的预防

介绍了封口墙板的铸造工艺及裂纹的预防措施。     

我国大学学院地位浅析

学院制是当今国内外大学通行的大学内部管理形式.从理论上讲,学术地位应是学院地位的核心,行政权力只是为学院的学术地位服务的.但在现实中,学院的学术地位低、行政权力虚,且地位既不确定也不稳定,还不同程度地存在着责、权、利分离的现象.影响学院现实地位的原因很复杂,既有大学的办学理念和发展定位,也有学院的设置依据、重点职能及其完成情况,还有学院规模、特色、财力状况、人际关系、开放性、下设专业的现状和发展前景等.这样的地位现状对大学使命和职能的完成也会造成不良的影响.通过分析,本文还对大学学院的未来地位做了方向性的预测.     

Investigation of the Phase Relations in the Al-Rich Alloys of the Al-Sc-Hf System in Solid State

Using electrical resistivity measurements, optical microscopy, and scanning electron microscopy (SEM) with energy dispersive x-ray analysis (EDS), the combined solubility of Sc and Hf in solid Al and the phases in equilibrium with Al solid solution at 600, 500, and 400 °C were studied. The investigation indicated the progressive decrease of the total solubility of Sc and Hf in solid Al with increasing Sc/Hf ratio in the alloys and decreasing temperature. ScAl₃ and HfAl₃ were observed in equilibrium with Al without formation of a continuous solid solution between them. Based on the established extension of the Al solid solution and also extensions of the ScAl₃ + (Al) and HfAl₃ + (Al) phase fields, the partial isothermal section of the Al-Sc-Hf phase diagram at 600 °C was constructed.     

二辊轧机联轴器连接螺栓断裂事故分析

以实测为根据，对二辊不可逆轧机主传动系统联轴器上的连接螺栓进行了受力分析和理论计算，找出了连接螺栓的断裂原因。     

Changes in the properties and composition of cementite in the process of graphitization

Metal Science and Heat Treatment -     

制钛过程中阴极钙钛矿的形成与阳极溢出气体间的关系

采用FFC剑桥工艺在熔融CaCl₂中电解二氧化钛时,钙钛矿是阴极上不可避免形成的相。本文研究了在制备钛的过程中,阴极钙钛矿的形成与阳极释放气体的关系。结果表明,阴极上相的形成主要有三个阶段,包括钙钛矿的形成、钙钛矿的脱氧及钛的低价氧化物脱氧为TiO、和TiO到Ti的脱氧。尽管分解电压低于CaCl₂,但阴极形成的钙钛矿与从阳极释放的气体密切相关。由于短时间内钙钛矿的形成造成过电压,因而阳极释放出氯气,氯气的量取决于TiO₂和电解过程中产生的不同低价钛的量。当钛的低价氧化物介于Ti₃O₅和TiO₂之间时,在第一脱氧阶段TiO₂和氯的质量比为9：2到46：2。在氯气释放的过程中阳极没有明显的消耗。钙钛矿的形成和Ti₂O的脱氧是在熔融CaCl₂中电解制备钛的主要限制性环节。从TiO₂到Ti的总电流效率是24.07％。目前第一阶段的电流效率在22.37％~44.74％之间,第二阶段在30.18％~37.72％之间。     

型腔模设计中推杆直径的确定

在型腔模设计中 ,推杆直径大小的确定一般是根据经验或依据类比法确定 ,这样确定的推杆往往与生产实际有一定的差距 ,通过对推杆的受力状况进行分析 ,从理论计算角度对推杆直径进行确定。