GM模型的几何性质及统计检验

以空间向量几何理论为基础，详细地分析了Ｇａｕｓｓ－Ｍａｒｋｏｖ线性模型的几何性质；在实现了模型图形化描述的基础上，利用各解向量的几何及统计性质构造出了不同情形下的统计检验方法和相应的检验统计量，为全面、深入地研究和灵活运用该模型提出了一种简洁直观的数学方法     

Ni3Al中B和Mg的非平衡晶界共偏聚

在1023－1373K的初始温度和0.05-268.91K/s的冷速范围内，用Auger剖层分析确定含B和Mg的Ni3Al合金中B和Mg的非平衡晶界共偏聚行为，按照溶质－空位复合体迁移机制所导出的描述非平衡晶界偏聚的扩散速率方程解析表达式，很好地模拟了本实验结果，并确定了Ni3Al-B-Mg合金中B及B－空位复合体，Mg及Mg-空位复合体的扩散系数及复合体激活能。     

An extension of Wagner's analysis of competing scale formation

Wagner's criterion to predict the minimum concentration of solute (N _B(min) ⁰ )necessary for the exclusive formation of its scale has been modified to incorporate both thermodynamic and kinetics requirements. The analysis presented here involves a receding alloy/scale interface for which the composition of the alloy at this interface is governed by thermodynamic equilibrium between the two competing scale phases and the base alloy. This is a more rigorous analysis than that of Wagner's, who assumed the alloy/scale interface to be immobile and the solute composition at the interface to be zero. A comparison is made between values of N _B(min) ⁰ found experimentally and those predicted by Wagner's and the present criterion for a number of alloy-gas systems. It is shown that the criterion developed in the present analysis can often provide a better approximation of the actual N _B(min) ⁰ .The expressions derived from the present analysis have been extended also in a semiquantitative manner to provide a criterion for the minimum amount of solute in the alloy required for the transition from internal to external scale formation.     

Monte-carlo modeling of grain growth in Zr equal channel angular pressed and recrystallized

Grain boundary character distribution in equal-channel-angular pressed Zr was studied. Using a die design of 90°/20° and an operation temperature of 350°C. The initial grain size of 20 μm was reduced to about 270 nm with 4 passes via route B_c. The grain growth kinetics of the recrystallized state was obtained by experiment and Monte-Carlo computer simulation, respectively, which showed good agreement. Based on kinetics and morphological characteristics, it was concluded that the grain coarsening mechanism was governed by normal grain growth. No sign of abnormal grain growth was detected either in the experiment or in simulation despite taking into consideration anisotropy in grain boundary energy as well as its mobility. This indicates that grain boundaries produced by severely deformed Zr are stable against explosive coarsening. The evolution characteristics of the microstructure in the present ECA pressed and recrystallized Zr differed from those of cold rolled Ti in that the grain boundary misorientation distribution and texture were rather stable during grain growth. Jointly Appointed by the Center for Advanced Aerospace Materials This article is based on a presentation made in the 2002 Korea-US symposium on the “Phase Transformations of Nano-Materials,” organized as a special program of the 2002 Annual Meeting of the Korean Institute of Metals and Materials, held at Yonsei University, Seoul, Korea on October 25–26, 2002.     

钛合金中亚晶的电子显微镜观察

用透射电子显微镜观察了TC6钛合金在高温退火过程中形成的亚晶(Subgrain)。合金经850℃,920℃退火后炉冷和空冷,在初生α相晶粒内形成亚晶,多为成簇分布的狭长形状,亚晶的数量随退火后冷却速度的增加而减少。亚晶界(Subgrain boundary)是由位错构成的,亚晶的形成是多边化(polygonization)的结果。     

Ni3Al合金中晶界与位错交互作用的研究

运用嵌入原子法势函数和静态驰豫最陡梯度的计算方法,原子模拟了Ni_3Al合金中晶界与位错的交互作用.主要研究了晶界与位错交互作用的能量特征、晶界结构单元的畸变行为和晶界附近位错的核心结构,并分析讨论了各种因素对它们的影响以及与Ni_3Al晶界韧脆行为之间的关系     

TiAl 合金中的γ→α析出转变行为

研究了Ti-48Al和Ti-48Al—0．8B合金中的γ→α析出转变，分析了α析出相的生长形态、晶体学特征、生长动力学及α／γ相界面结构。结果显示α相从γ相中析出有两种方式：一种是从γ晶粒内沿{111}，晶面以片状形貌析出，且α相与γ基体保持共格位向关系；另一种则是在γ晶界上通过不连续析出转变，以不规则的块状形貌析出，并向着晶界一侧与之无位向关系的γ晶粒内生长。添加0．8％(摩尔分数)B能显著降低γ晶粒内片状α析出相的形核率，并抑制α相生长。HREM分析表明：片状α相是在γ相的堆垛层错上形核，并通过“台阶-凸起-扭折”机制生长；α／γ相界面上复杂层错的存在及台阶形核率低是片状α相沿厚度方向生长缓慢的主要原因。     

连轧管生产工艺的演变与选择

介绍了浮动芯棒、限动芯棒和三辊式限动芯棒连轧管工艺的发展历程。分析了各种型式连轧管机的适用条件；并认为，各种机型装备的发展与市场需求紧密相关，单纯从技术上考虑，而追求同一机型不能带来良好的经济效益     

ZnO压敏陶瓷的非线性功能添加剂

本文采用单元掺杂与多元掺杂的方法，系统研究了几种过渡金属氧化物添加剂在控制ＺｎＯ压敏陶瓷非线性方面的作用，并根据金属阳离子外壳层电子结构稳定性和缺陷化学反应进行了分析，认为阳离子具有不饱和外层电子结构且半径与Ｚｎ＾２＋离子相近的过渡金属氧化物能改善ＺｎＯ压敏陶瓷非线性。     

Electrical and optical study of Cu(In, Ga)Se2 co-evaporated thin films

Co-evaporation technique from three sources was used to prepare Cu(In, Ga)Se₂ polycrystalline thin films for photovoltaic conversion. Their conductivity was studied in the range 20–300 K. The grain boundary scattering mechanism is mainly responsible for the diffusion process in the latter materials. In the low temperature region, we interpret the data in terms of Mott law and the analysis is very consistent with the variable range hopping. However, thermoionic emission is predominant at high temperatures. When the conductivity deviates from the classical grain boundary conduction models, inhomogeneity is then considered and parameters such as the standard deviation and the mean potential barrier height are derived. Transmittance measurements yielded band gap values of 1.07 and 1.64 eV for CuInSe₂ and CuGaSe₂, respectively.