Her-Yueh Huang
,
Kuang-Hung Tseng
金属学报(英文版)
The effects of the process parameters on the joint quality of TO-Can using resistance projection welding were investigated. A capacitor discharge stored energy welding machine was used for joining caps and headers both coated with nickel SPCC steel. The electrode materials used in this study were brass and W- Cu alloy. Experimental results indicated that the peak current of the W-Cu electrode was higher than that of the brass electrode, irrespective of the operating pressure variation. Increased operating pressure influenced the interfacial heat generation and nugget formation. The nugget area increased rapidly with increasing charging voltage, resulting in expulsions and electrodes getting stuck. An acceptable welding zone was found in the relationship between the charging voltage and the operating pressure. Representative test specimens of the acceptable welding zone satisfactorily passed the helium leak test. The microscopic morphology of the nugget showed a recrystallized fine grain structure resulting in the nugget being harder than with the HAZ.
关键词:
Projection welding
Journal of Physics-Condensed Matter
Recent theoretical studies indicate that metastable rocksalt CaN, SrN, and BaN exhibit half-metallic ferromagnetism (Volnianska and Boguslawski 2007 Phys. Rev. B 75 224418; Gao et al 2008 Phys. Lett. A 372 1512), and further experiments confirm the existence of self-assembled metastable CaN nanostructures (Liu et al 2008 Surf. Sci. 602 1844). We here use the first-principles method based on density functional theory to investigate the structural, electronic, and magnetic properties of the (111) surfaces of CaN and SrN and the interfaces of CaN/InN(111) and SrN/GaP(111). The surface stability from the calculated surface energy indicates that the N-terminated (111) surface is more stable than the Ca (Sr)-terminated (111) surface in the N-rich environment. For CaN and SrN, both anion-and cation-terminated (111) surfaces preserve the half-metallic characteristics of the bulk. Interfacial studies indicate that the half-metallicity of bulk CaN is retained in two of the four possible configurations of the CaN/InN(111) interface, while for the interface of SrN/GaP(111) only one interfacial configuration shows half-metallicity. Furthermore, we assess the interfacial adhesive strength for all the possible different configurations of the interfaces studied here by calculating the interface adhesion energies.
关键词:
molecular-beam epitaxy;room-temperature;ferromagnetism;1st-principles
常永勤
,
介万奇
,
郭喜平
,
陈福义
,
安卫军
功能材料
研究了ACRT-B法生长的Mn0.1Cd0.9In2Te4晶体中界面的形状和各组元沿轴向的分布规律及其分凝因数.发现结晶界面为椭球形;采用理想配比生长MnxCd1-xIn2Te4晶体,其4种组元并不按(Mn,Cd):In:Te=1:2:4比例结晶,而是要重新分布;通过数学方法处理实验数据得到Mn,Cd和In的分凝因数在α相区分别为1.286、1.9257和0.7294,在β相区则分别为1.12、1.055和0.985.
关键词:
ACRT-B法
,
MnxCd1-x In2Te4
,
界面
,
分凝因数
Journal of Materials Research
Three typical interactions of persistent slip bands (PSBs) with different types of grain boundaries (GBs) were investigated and analyzed in fatigued copper crystals. The results show that PSBs cannot transfer through all types of large-angle GBs, regardless of their orientation with respect to the stress axis. Secondary slip was often observed near the GBs, leading to strain incompatibility. When the slip systems of the two adjacent crystals are coplanar, the transmission of a PSB across a GB strongly depends on the slip directions of the two adjacent crystals. It was found that only the low-angle GBs can be passed through by PSBs, and accordingly they are insensitive to intergranular fatigue cracking. For a special copper bicrystal with coplanar slip systems, the ladderlike dislocation arrangements within the adjacent PSBs become discontinuous and a dislocation-affected-zone appears near the GB due to the difference in the slip direction of the two adjacent crystals. Therefore, the necessary conditions for the transmission of a PSB across a GB are that the neighboring grains have a coplanar slip system and identical slip directions.
关键词:
cyclic deformation-behavior;fatigued copper polycrystals;dislocation-structures;single-crystals;bicrystals;metals;zones
常永勤
,
安卫军
,
郭喜平
,
介万奇
无机材料学报
采用Bridgman法生长了x为0.1,0.22和0.4的四元稀磁半导体化合物MnxCd1-xIn2Te4晶体.研究了三根晶体中相的形貌、结构、成分和Mn0.1Cd0.9In2Te4晶体中各组元沿轴向和径向的成分分布.晶体生长初始端的组织为α+β+β1,随着生长的进行,形成β相的单相区.在晶锭末端,形成In2Te3类面心立方结构化合物.组分x增大后,MnxCd1-xIn2Te4晶体的吸收边向短波方向移动,禁带宽度则线性增大.磁化率测量结果表明:晶体在高温区的x-1-T曲线服从居里-外斯定律,在低温区(<50K)则表现出顺磁增强现象.
关键词:
MnxCd1-xIn2Te4
,
compositional distribution
,
infrared transmission spectra
,
mag- netic susceptibility
常永勤
,
安卫军
,
郭喜平
,
介万奇
无机材料学报
doi:10.3321/j.issn:1000-324X.2003.02.004
采用Bridgman法生长了x为0.1,0.22和0.4的四元稀磁半导体化合物MnxCd1-xIn2Te4晶体.研究了三根晶体中相的形貌、结构、成分和Mno.1Cd0.9In2Te4晶体中各组元沿轴向和径向的成分分布.晶体生长初始端的组织为α+β+β1,随着生长的进行,形成β相的单相区.在晶锭末端,形成In2Te3类面心立方结构化合物.组分x增大后,MnxCd1-xIn2Te4晶体的吸收边向短波方向移动,禁带宽度则线性增大.磁化率测量结果表明:晶体在高温区的x-1-T曲线服从居里一外斯定律,在低温区(＜50K)则表现出顺磁增强现象.
关键词:
MnxCd1-xIn2Te4
,
成分偏析
,
红外透射光谱
,
磁化率
Y.H. He
,
B. Y. Huang
,
Y. Liu and Y.X. Liu (Powder Metallurgy Research Institute
,
Central South University of Technology
,
Changsha 410083
,
China)
金属学报(英文版)
The effects of a new technology, multi-step thermo-mechanical treatment, on the microstructure, deformation substructure and mechanical properties at ambient and elevated tempemture of can-forged Ti-33 Al-3 Cr-0.5Mo (wt%) Alloy were investigated.The results show that, after multi-step thermo-mechanical treatment of can-forged specimens, homogeneous, fine microstructures can be obtained in the whole TiAl-based alloy specimens. Furthermore, the specimen with homogeneous and fine full lamellae microstructure demonstrutes excellent comprehensive mechanical properties at ambient and elevated temperature.
关键词:
TiAl-based alloy
,
null
,
null
朱林晖
,
丁马太
功能材料
在研究玉米淀粉(corn starch,CS)与甲基丙烯酸甲酯(MMA)接枝共聚反应时发现,硝酸浓度为0.1mol/L、硝酸铈铵(CAN)/CS质量比为1/6、MMA/CS质量比为3/2是兼顾单体转化率(C)、接枝率(G)和接枝效率(GE)的最佳反应条件;同时发现,该反应中均聚物的生成不仅可由CAN直接引发,还可能因淀粉自由基或淀粉接枝物自由基的链转移而引发.
关键词:
淀粉
,
接枝共聚
,
硝酸铈铵
,
均聚物
