M. Yamamoto and T. Ogata (Central Research Institute of Electric Power Industry
,
2-11-1
,
Iwado Kita
,
Komae-shi
,
Tokyo 201-8511
,
Japan)
金属学报(英文版)
In order to investigate creep-fatigue life characteristics of Inconel 738LC, fatigue and creep-fatigue tests were carried out at 850℃. Significant life reduction to 30% to 50% of normal fatigue life, occurred when a strain hold period was introduced at the minimum compressive strain. Test results showed that the degree of life reduction did not depend on the length of hold time. To clarify the creep-fatigue damage mechanisms under creep-fatigue loading, in-situ SEM observations were carried out during the tests. In the tensile strain hold test, multi-site grain boundary cracking was observed from the beginning of the test. On the other hand, only a single main crack was observed in the compressive strain hold test. The crack propagated in an intergranular manner and it was different from the features observed under cyclic fatigue conditions. Through detailed observation, it was found that grain boundary sliding damage occured at most surface grain boundaries.
关键词:
superalloy
,
null
,
null
Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences
An ab initio method based on the density functional theory has been employed to investigate the behaviours of the bimetallic Ag(2)-doped silicon clusters at a size of n = 1-11. The possible geometrical configurations, growth-pattern behaviours, stabilities, energy gaps, and electronic properties are presented and discussed. The optimized geometries reveal that the silicon atom surface-capped and silver atom substituted 3D structures are dominant growth patterns. The calculated averaged binding energy, fragmentation energy, and the second-order difference of energy manifest that the most stable structures of Ag(2)Si(n) (n = 1-11) clusters are Ag(2)Si(2) and Ag(2)Si(5) isomers, which is in qualitative agreement with the AgSi(n) clusters. In addition, the gap between highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) exhibits that the Ag(2)Si(3) and Ag(2)Si(5) isomers have dramatically enhanced chemical stability. Natural population analysis shows that the charge-transfer phenomena are coincidence with the AgSi(n) clusters but different from Mo(2)Si(n) systems. Furthermore, the dipole moments of stable Ag(2)Si(n) (n = 1-11) display a pronounced odd-even oscillation with the number of silicon atoms.
关键词:
Ag-Si Cluster;Geometric Configuration;Density Function Method;laser-absorption spectroscopy;flight mass-spectroscopy;supersonic;molecular-beam;small silicon clusters;gold silicides;copper silicide;states;silver;ions
郑国华
,
宋小龙
,
赵阳
材料开发与应用
通过疲劳升降法对汽轮机叶片钢2Cr11Mo1NiWVNbN在100℃下的疲劳强度(107)进行测定,分别用经验公式、Basquin模型和Langer模型对测定结果进行计算和验证.结果表明:2Cr11Mo1NiWVNbN钢在100℃下的条件疲劳极限为530 MPa,大于由经验公式计算的411 MPa,这是由于M23C6析出相弥散强化及Cr和Mo元素提高了钢的淬透性所致;Langer模型对条件疲劳极限的拟合结果比Basquin模型更接近实测值,且Langer模型拟合得到的不同存活率下条件疲劳极限的分散性较小,建议在计算2Cr11Mo1NiWVNbN钢的疲劳强度时采用Langer模型.
关键词:
升降图
,
疲劳极限
,
P-S-N曲线
,
弥散强化
王建国
,
王红缨
机械工程材料
doi:10.3969/j.issn.1000-3738.2003.08.005
为探索加载频率对轴向加载(应力)疲劳寿命的影响,在高频疲劳试验机和电液伺服疲劳试验机上分别对1Cr11Ni20Ti2B钢板材进行了不同应力水平下的疲劳断裂寿命测试,同时在相同应力水平下分别在两台试验机以不同的加载频率进行了断裂寿命对比试验.结果表明,随着加载频率的降低,断裂寿命将缩短,但频率在20～135Hz范围内时,加载频率对疲劳断裂寿命影响不显著,在不同频率下测试的断裂寿命可以描述在同一条寿命曲线上.
关键词:
应力疲劳
,
频率
,
疲劳寿命
陆景彬
,
刘运祚
,
孙亮
,
杨东
,
梁国栋
,
王守宇
,
马英君
,
赵广义
,
李险峰
,
崔兴柱
,
李明非
,
霍俊德
,
曾国模
,
竺礼华
,
吴晓光
原子核物理评论
doi:10.3969/j.issn.1007-4627.2005.02.003
在稀土区奇奇核πh11/2(×)νi13/2转动带中, 系统地观测到随转动频率或角动量增加, B(M1)/B(E2)曲线表现出所谓parabola-like形状, 即在增加到某一转动频率或自旋后, B(M1)/B(E2)比值快速增强. 基于推转模型和粒子转子模型关于奇奇核二准粒子转动带磁偶极约化跃迁几率的描述, 对稀土区双奇核的这一行为进行了讨论. 指出该现象的发生与νi13/2准中子转动顺排特性密切相关. B(M1)/B(E2)比值在接近第二带交叉(即BC准中子对顺排)的较高频率处的增强效果, 可以理解为主要来源于带交叉引起的波函数中混合四准粒子成分的结果. 通过对B(M1)/B(E2)比值的增强效果发生在较低频率处的分析, 对稀土区奇奇核πh11/2(×)νi13/2带角动量耦合图像有了进一步认识.
关键词:
高自旋态
,
奇奇核
,
电磁跃迁特性
,
顺排
孟波
,
郭万林
,
姜燕
机械工程材料
利用扫描电镜和原子力显微镜等方法研究了在偏酸性环境条件下,表面形貌对1Cr11Ni2W2MoV不锈钢耐腐蚀性能的影响.结果表明:1000#砂纸抛光试样的耐腐蚀性能最好,机械磨削试样次之,800#砂纸抛光试样的最差;试样的耐腐蚀性能并不是随着表面粗糙度的降低而增强;这主要是由于1000#砂纸抛光试样具有较高的亚稳态和稳定孔蚀电位,而800#砂纸抛光试样比磨削试样更容易在表面形成腐蚀微电池所引起的.
关键词:
表面形貌
,
耐腐蚀性能
,
不锈钢
郑建东
,
葛秀涛
,
侯豹
材料导报
采用异丙醇盐水解法制备Ba1x/2KxNiAl11O19 (x=0,0.5,1.0,1.5,2.0)催化剂.通过BET模型计算了其比表面积,用XRD和DSC-TG等技术及甲烷燃烧实验考察了催化剂的物理化学性能,研究了钾离子掺杂量对催化剂的结构以及对甲烷催化燃烧活性的影响.结果表明:催化剂在1200℃焙烧后可以形成完整的六铝酸盐晶型,同时具有较好的催化性能和高温稳定性,不同量的K和Ba离子掺杂对于催化剂的比表面积及孔径有较大的影响.Ba0.25K1.5 NiAl11O19催化剂具有较大的比表面积和较高的活性,1200℃焙烧后比表面积为61m2/g,催化甲烷燃烧的完全转化温度T90％为750℃.
关键词:
六铝酸盐
,
掺杂
,
甲烷催化燃烧
,
催化活性
Applied Physics Letters
We have succeeded in synthesizing PrFe11V1-xTix (x=0.2-1) compound and their nitrides with the ThMn12-type structure. The phase formation and magnetic properties have been investigated by x-ray diffraction, differential thermometric analysis, and magnetic measurement. The stable temperature range of the 1-12 phase for PrFe11V1-xTix alloys has been determined as a function of Ti content. PrFe11V compounds with the ThMn12-type structure do not exist and PrFe11Ti compounds with the TnMn(12)-type structure are obtained by annealing in a narrow temperature range between 1303 and 1383 K. Furthermore, 1-12 phase with the ThMn12-type structure can be obtained at lower temperature and wider temperature range with decreasing Ti content x (0.2 less than or equal to x less than or equal to 1). PrFe11V1-xTixNy with x=0.2-1 has a T-c of about 730-785 K, B-a larger than 8 T and M-s in the range 144-148 emu/g. These intrinsic magnetic properties are highly favorable for permanent magnet applications. As a preliminary, an intrinsic coercivity of 5.4 kOe is obtained for PrFe11V0.5Ti0.5Ny at room temperature by using mechanical alloying technique. (C) 1997 American Institute of Physics.
关键词:
