赵恩广
,
李君清
,
W.Scheid
原子核物理评论
doi:10.3969/j.issn.1007-4627.2005.04.004
简单介绍了兰州-北京-吉森合作组对合成超重核的重离子反应进行的初步研究.研究的重点是熔合阶段的反应机制.在原有双核模型的基础上做了一些改进,把耗散相对运动过程与核子转移过程耦合起来,从更微观的角度来描写双核系统向全熔合复合核的演化.在双核过程中的每一步求解主方程,不对驱动势做谐振子近似.同时,还探讨了原子核形变与相对取向对驱动势的影响,存活几率与复合核蒸发中子的奇偶效应,以及入射道中原子核非弹性激发对俘获截面的影响等.
关键词:
重离子熔合反应
,
超重元素
,
主方程
,
准裂变
,
复合核衰变
HUANG Huimin CHEN Xinmin Central South University of Technology
,
Changsha
,
China HUANG Huimin Associate Professor
,
Department of Chemistry
,
Central South University of Technology
,
Changsha
,
China
金属学报(英文版)
The nature of the oxygen contained in β-W was investigated with DSC,X-ray analysis on quenched samples and Auger spectroscope.It was shown that the oxygen contained in nonpyrophoric β-W consists of the reversibly chemisorbed oxygen and the interstitial oxygen which could form an interstitial solid solution with β-W.It seems better to consider β-W to be a metastable phase of tungsten with the interstitial oxygen as stabilizer.
关键词:
tungsten
,
null
,
null
,
null
Physical Review B
The effect of W on the structural stability of TiAl intermetallic systems and the site preference of W in B2 and L1(0) TiAl were studied based on first-principles calculations. It was found find that about 15 at. % W addition, in good agreement with experiment, is required to stabilize the B2 structure in a TiAl base alloy. W was predicted to occupy Al sites in the B2 phase, but Ti sites in the L1(0) phase. The B2-stabilizing effect of W and its site preference can be explained perfectly on the basis of the pseudogap effect and the strong covalent W-Ti bonding. The strong W-Ti bonding pairs are maximized when W occupies Al sites in B2 TiAl. But when W occupies Al sites in L1(0) TiAl, the W-Ti bonding is weakened by the existence of Al in the alternating (002) plane, which can, however, strengthen the in-plane W-Ti bonding when W occupies Ti sites.
关键词:
gamma-titanium aluminides;electronic-structure;microstructure;deformation;systems;alloys
Xiaobo LI
,
Youqing XIE
金属学报(英文版)
doi:10.1016/S1006-7191(08)60099-X
The valence bond structure of substitutional BCC based Ta-W alloys is studied using characteristic crystal (CC) theory. This theory is based on cluster statistics of random alloys. By studying the correlativity between energy and volume of the CC in Ta-W alloys, the valence bond structure of CC is determined by the energy and shape method. Then, following additive law of CC, the valence bond structure of Ta-W alloys is calculated. It is found that the outer shell valence electronic distribution of Ta-W alloys shows a continuous change in the whole composition range. The covalent electrons ec(dc, sc, and pc) increase, whereas near free electrons ef decrease with increasing W concentration. The bond length and single-bond radius decrease, whereas bond energy and bond valence increase with increasing W concentration. The mechanism of solid solution strengthening of Ta-W alloys is analyzed based on their valence bond structure.
关键词:
Valence bond structure
,
null
Xiaobo LI
金属学报(英文版)
The characteristic crystal model is applied to the study of phase stability and thermodynamics in substitutional bcc-based Ta-W alloys. The basic principle and method of alloy thermodynamics which is described by the characteristic crystal model is introduced in detail. The Gibbs energy of various phases including both disordered and ordered phases of the Ta-W system are evaluated. The phase diagram of Ta-W alloys is assessed and predicted. The results are in good agreement with experiments and better than that of first principle.
关键词:
Ta-W alloys
,
phase diagram
,
characteristic crystal model
,
thermodynamics
,
phase stability
Bo YANG
金属学报(英文版)
A series of hexagonal close-packed (HCP) Co-W thin films were deposited by sputtering on surface oxidized silicon substrates at 300℃. A linear dependency of saturation magnetization (Ms) on W content was found up to about 9~at.~pct W, and then it underwent an increased Ms vs. W content curve as compared to the initial linear dependency. The thermal magnetization technique was used to confirm that the increased Ms behaviour is correlated to the phase separation of the Co-W thin films. The phase separation behaviour was also found to be dependent on W content and the reason was discussed in detail. Finally an interesting composition range was suggested to be about 13at.pct-17 at. pct W for the Co-W thin films, in which they exhibit much higher magnetic anisotropy energy than Co-Cr thin films and improved phase separation.
关键词:
Magnetic recording media
朱立群
,
李卫平
电镀与涂饰
doi:10.3969/j.issn.1004-227X.2004.05.003
通过在浓硝酸、w=5% NaCl溶液、c＝1 mol/L H2SO4溶液中的浸渍试验,研究了不同基体上的Ni-W非晶态合金镀层的耐蚀性;通过测定在w=5% NaCl溶液及c=1 mol/L的HNO3溶液、H2SO4溶液、HCl溶液中的阳极极化曲线,研究了Ni-W非晶态合金镀层薄膜本身的耐蚀性;采用线性极化方法对Ni-W-B非晶态合金镀层在w=5% NaCl溶液、c＝1 mol/L H2SO4溶液及HNO3溶液中的腐蚀速度进行了测定,并测定了以上2种非晶态合金镀层的硬度与耐磨性.结果表明,非晶态的Ni-W、Ni-W-B镀层比晶态镀层的耐腐蚀性能要好,而Ni-W-B 非晶态合金镀层比Ni-W非晶态合金镀层的耐蚀性能又明显提高;经热处理后,Ni-W-B非晶态镀层的硬度值明显高于Ni-W非晶态镀层,耐磨性能都提高了1倍以上.Ni-W、Ni-W-B非晶态镀层极有望成为一种比较好的代铬镀层.
关键词:
代铬镀层
,
非晶态镀层
,
Ni-W
,
Ni-W-B
,
耐蚀性能
ZHU Kai University of Science and Technology of China
,
Hefei
,
China WANG Chongyu Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
China Central Iron and Steel Research Institute
,
No.13
,
Taipingzhuang
,
Beijing
,
China
金属学报(英文版)
The calculation of electronic structure of γ'-Ni_3Al phase with or without Mg and W by the Recursion and LCAO methods clarified that Mg and W atoms lose their outer electrons par- tially after they entered γ'-Ni_3Al.It causes the reduction of the radii of the atoms.So it is preferable for Mg atom to enter γ'-phase by the substitution.The interaction between Mg and γ'-phase matrix may be strengthened and a more stable structure of γ'-phase may be formed while Mg and W entered γ'-Ni_3Al simultaneously.
关键词:
superalloy
,
null
,
null
,
null
