H.B.Dong
材料科学技术（英文）
A numerical model Alloy/M has been applied to investigate the microsegregation in Al-4.45 wt pct Cu alloy. The calculated data were compared with the experimental measurements for samples solidified at different cooling rates. Discrepancies in solute concentration occur between the experimental observations and calculated results. Reasons for the discrepancies were discussed, and the effect of dendrite joining at a later stage of solidification on the microsegregation was investigated. Calculations that have included this effect showed a better fit with experimental results.
关键词:
Microsegregation
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null
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null
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null
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null
毕大森
,
武晋
,
张建
,
彭本栋
材料开发与应用
doi:10.3969/j.issn.1003-1545.2009.01.003
高强度烘烤强化(BH)钢是汽车覆盖件用的高强度钢板.本文通过试验对汽车用高强度钢板B180H1的力学性能、成形性能、烘烤硬化性能和抗凹陷性能进行了全面的研究,并与DC04钢板的各项性能进行了比较.使用NADDRG模型对B180H1钢的成形极限进行了预测.试验结果表明,B180H1的力学性能优于DC04,成形性能不低于DC04,且B180H1的烘烤硬化性能及抗凹陷性能方面均优于DC04.B180H1钢板的实冲壳体也具有良好的成形性能.
关键词:
汽车轻量化
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高强度钢板
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烘烤硬化
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成形性能
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抗凹陷性
Y.L. Chen(Department of Materials Science and Engineering
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Zhejiang University
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Hangzhou 310027
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China)
金属学报(英文版)
Internal friction measurements on binary and ternary α-phase alloys of Pd with hydrogen and boron have been performed with a torsion pendulum and by observing the cttenuation of ultrasonic pulses. A pronounced damping maximum of binary Pd-B alloys at 220K and measuring frequencies of about 4Hz could not be established at a frequency of 15MH. Ternary Pd-B-H alloys show an additional damping maximum besides the hydrogen Zener effect, which is interpreted in terms of a changed jump frequency of hydrogen in the neighborhood of boron atoms.
关键词:
Pd-B-H alioy
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null
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null
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null
Physical Review B
By using a first-principles plane-wave pseudopotential method, the energetics and electronic structure of Sigma5(210) grain boundary (GB) and the (210) surface of undoped as well as B- and/or H-doped Ni3Al are investigated. The geometric structures of the GBs and surfaces are fully relaxed by minimizing the total energy and interatomic force. The results show that B induces a large lattice expansion but H does not. Both B and H "prefer" to occupy the Ni-rich hole at the GB or surface but not the Ni-deficient one. The segregation energies of B and H as well as the interaction energy between them at the GB and surface are calculated. The calculation indicates that B segregates more strongly to the GB than to the surface, which results in an increase in the Griffith work of the GB and, therefore, in agreement with the experiments, improves the ductility of Ni3Al. Contrary to the case of B, H segregates more strongly to the surface than to the GB, which results in a decrease in Griffith work and confirms H as an embrittler for Ni3Al. The calculation of the interaction energy between B and H demonstrates that B and H repel each other. Consequently, B may block the site of occupation of H at the GB, and restrain the H-induced embrittlement. To understand the mechanism of the obtained energetic features, the electronic densities of states (DOSs) are calculated. A comparison of the total DOSs between the B-doped GB and undoped as well as H-doped ones shows that B increases the hybridization of the GB, which contributes to the enhanced binding of the B-doped GB over the undoped and H-doped ones. When the site of B changes from bulk to GB to surface, the hybridization between B and Ni decreases accordingly. It is proposed that the segregation behavior of B at the GB and surface is dominated by the competition between B(p)-Ni(d) bond energy and the strain energy induced by B. The preference of B for the Ni-rich interstice in Ni3Al is explained by the repulsive interaction between B and Al atoms resulting from the hybridization between their electrons when they are close to each other. The repulsion between B and H can also be explained by the same electronic structure mechanism as that for the B-Al interaction. The segregation of B at surface shifts the DOS of its nearest neighbor Ni to lower energy. This may increase the chemisorption potential energy of H2O on Ni3Al surface and, therefore, decrease the reactivity of the surface, inhibiting the environmental embrittlement of Ni3Al.
关键词:
intergranular fracture;environmental embrittlement;polycrystalline;ni3al;water dissociation;first-principles;metal-surfaces;boron;segregation;ductility;hydrogen
张善业
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高怡斐
物理测试
对马钢生产的耐火H型钢MGFR490B和Q345B H型钢进行了对比试验研究,完成了高温拉伸和高温持久两项力学性能测试和对两种钢微观组织的观察研究.结果表明,耐火H型钢MGFR490B的组织为多边形铁素体+珠光体+少量贝氏体混合多相组织,此种组织在高温下能保持很好的稳定性,并能在高温下析出合金碳化物,这对降低耐火H型钢MGFR490B的室温屈强比和保持高温屈强比小的波动范围有益.耐火H型钢MGFR490B获得了比Q345B H型钢好的高温强度性能,这与耐火钢的混合多相组织及添加合金元素密不可分.耐火H型钢MGFR490B在600℃高温下能保持高的强度,并且其持久断裂时间超过3 h,满足耐火钢的性能指标要求.
关键词:
耐火钢
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高温拉伸
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高温持久
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屈强比
张善业
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高怡斐
物理测试
对马钢生产的耐火H型钢MGFR490B和Q345B H型钢进行了对比试验研究，完成了高温拉伸和高温持久两项力学性能测试和对两种钢微观组织的观察研究。结果表明，耐火H型钢MGFR490B的组织为多边形铁素体﹢珠光体﹢少量贝氏体混合多相组织，此种组织在高温下能保持很好的稳定性，并能在高温下析出合金碳化物，这对降低耐火H型钢MGFR490B的室温屈强比和保持高温屈强比小的波动范围有益。耐火H型钢MGFR490B获得了比Q345B H型钢好的高温强度性能，这与耐火钢的混合多相组织及添加合金元素密不可分。耐火H型钢MGFR490B在600 ℃高温下能保持高的强度，并且其持久断裂时间超过3 h，满足耐火钢的性能指标要求。
关键词:
耐火钢
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high temperature tensile high temperature persistent
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yield ratio
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null
张蓓
,
张鹏
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王军
,
朱飞
,
曹兴忠
,
王宝义
,
刘昌龙
原子核物理评论
doi:10.11804/NuclPhysRev.30.04.471
室温下将130 keV，5×1014 cm-2 B离子和55 keV，1×1016 cm-2 H离子单独或顺次注入到单晶Si中，采用横截面试样透射电子显微镜(XTEM)和慢正电子湮没技术(SPAT)研究了离子注入引起的微观缺陷的产生及其热演变。XTEM观测结果显示，B和H离子顺次注入到单晶Si可有效减少(111)取向的H板层缺陷，并促进了(100)取向的H板层缺陷的择优生长。SPAT观测结果显示，在顺次注入的样品中，B离子平均射程处保留了大量的空位型缺陷。以上结果表明，B离子本身及B离子注入所产生的空位型缺陷对板层缺陷的生长起到了促进作用。
关键词:
单晶Si
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B和H离子注入
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H板层缺陷
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XTEM
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SPAT
Energy & Environmental Science
The Li-Mg-B-H system that is prepared from 2LiH + MgB(2) or 2LiBH(4) + MgH(2) possesses high hydrogen capacity and relatively favorable thermodynamics, but it is greatly restricted in practical hydrogen storage applications by problematic H-exchange kinetics. In the present study, TiF(3) was mechanically milled with a 2LiH + MgB(2) mixture and examined with respect to its effect on reversible dehydrogenation of the Li-Mg-B-H system. Experimental study showed that TiF(3) is highly effective for promoting the two-step dehydrogenation reaction in the Li-Mg-B-H system. Compared to the neat 2LiH + MgB(2) sample, the 2LiH + MgB(2) + 0.01TiF(3) sample exhibits significantly reduced dehydrogenation temperature and markedly enhanced dehydriding rate at both steps. Furthermore, the catalytic enhancement arising upon adding TiF(3) additive was observed to persist well in the hydrogenation/dehydrogenation cycles. Based on the results of phase analysis and a series of designed experiments, the mechanism underlying the observed property improvement is discussed.
关键词:
complex hydrides;libh4;tif3;kinetics;naalh4
孙保库
,
李宁
,
杜敏
材料保护
H62黄铜与B10铜镍合金是船舶海水管路系统中广泛使用的电偶对，为了探讨其匹配性，研究了2种材料在0，1，3，5m／s流速海水中的电偶腐蚀行为。通过自然腐蚀电位监测、电偶腐蚀试验、三维视频显微镜考察了海水流速对2种材料电偶腐蚀倾向、电偶腐蚀规律和微观腐蚀形貌的影响。结果表明：在不同流速海水中，H62黄铜与B10间存在明显的电偶腐蚀倾向，H62作为阳极，腐蚀加剧，B10作为阴极受到保护。结果还表明，随海水流速增大，电偶腐蚀效应γ先减小后增大，于3m／s海水中呈现极小值；电偶腐蚀流速敏感性因子A逐渐增大；H62试样呈现出更为明显的冲刷腐蚀形貌。
关键词:
电偶腐蚀
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流动海水
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B10铜镍合金
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H62黄铜
李海东
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徐成
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罗春燕
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高瑛
高分子材料科学与工程
将聚苯乙烯-聚氧乙烯-聚苯乙烯(PS-b-PEO-b-PS)与不同相对分子质量的聚氧乙烯均聚物(h-PEO)共混,研究三嵌段共聚物中间嵌段处于不同干湿刷条件下的PEO的结晶行为.利用差示扫描量热法(DSC)研究共混物的结晶、熔融行为,发现嵌段共聚物中PEO嵌段的相对分子质量与PEO均聚物的相对分子质量对共混物的干、湿刷形貌有很大的影响.同时可通过自成核方法有效地改变共混物的干、湿刷状态.利用X射线小角散射技术(SAXS)确认这种干、湿刷的相分离状态.
关键词:
热分析
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聚苯乙烯-聚氧乙烯-聚苯乙烯
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聚氧乙烯均聚物
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干刷
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湿刷
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结晶行为
