Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
材料科学技术（英文）
The effect of interstitial hydrogen on the cohesion of the Al Sigma=11(113) grain boundary (GB) is investigated based on the thermodynamic model of Rice-Wang using the first-principles density function calculation. The results indicate that interstitial H behaves as an embrittler from "strengthening energy" analysis. The reduced GB cohesion due to the presence of H at the GB is attributed to the low affinity between H and Al, and the weakened bonding of Al atomic pairs perpendicular to GB plane.
关键词:
hydrogen;grain boundary;Al-Mg alloys;pseudopotentials;1st-principles
Xiaoguang LIU
,
Xiaowei WANG
材料科学技术（英文）
The effect of interstitial hydrogen on the cohesion of the Al ∑=11(113) grain boundary (GB) is investigated based on the thermodynamic model of Rice-Wang using the first-principles density function calculation. The results indicate that interstitial H behaves as an embrittler from "strengthening energy" analysis. The reduced GB cohesion due to the presence of H at the GB is attributed to the low affinity between H and Al, and the weakened bonding of Al atomic pairs perpendicular to GB plane.
关键词:
Hydrogen
,
null
,
null
Physical Review B
By use of the linear-combination-of-atomic-orbital (LCAO) method for a cluster model, we studied the electronic structure of gamma-from Sigma 11 [1 (1) over bar0](11 (3) over bar) grain boundary doping with N and Mn atoms. The effect of the segregation on the cohesion of the grain boundary is investigated based on the Rice-Wang thermodynamic model. It is found that N could not only largely enhance the cohesion of the grain boundary but also eliminate the detrimental effect of Mn. The cosegregation effect of Mn and N on the cohesion of the grain boundary depends on where they segregate. Nitrogen could be reliably used in alloyed steels as an efficient strengthening element.
关键词:
electronic-structure;phosphorus segregation;stainless-steel;embrittlement;austenite;nitrogen;boron;impurities;fracture;metals
Journal of Physics and Chemistry of Solids
The layered ternary ceramics Ti3SiC2 and Ti3AlC2 are isostructural and can form Ti3Si1-xAlxC2 solid solutions combining the advanced properties of both compounds [H.B. Zhang, Y.C. Zhou, Y.W. Bao, M.S. Li, Improving the oxidation resistance of Ti3SiC2 by forming a Ti3Si0.90Al0.1C2 solid solution, Acta Mater. 52 (2004) 3631-3637; E.D. Wu, J.Y. Wang, H.B. Zhang, Y.C. Zhou, K. Sun, Y.J. Xue, Neutron diffraction studies of Ti3Si0.9Al0.1C2 compound, Mater. Lett. 59 (2005) 2715-2719; J.Y. Wang, Y.C. Zhou, First-principles study of equilibrium properties and electronic structure of Ti3Si0.75Al0.25C2 solid solution, J. Phys.: Condens. Matter 15 (2003) 5959-5968; Y.C. Zhou, J.X. Chen, J.Y. Wang, Strengthening of Ti3AlC2 by incorporation of Si to form Ti3Al1-xSixC2 solid solutions, Acta. Mater. 54 (2006) 1317-1322]. In the present work, the solid solutions of Ti3Si1-xAlxC2 (x = 0, 0.25, 0.33, 0.5, 0.67, 0.75, 1) are investigated by first-principle calculations based on pseudo-potential plan-wave method within the density functional theory framework. The results show that as Al content increases in the solid solution, all the bonds have weakened to certain extents, which lead to an unstable structure both energetically and geometrically. The calculated results are compared and discussed with the reported data for the Ti3Si1-xAlxC2 solid solutions. (c) 2007 Elsevier Ltd. All rights reserved.
关键词:
ceramics;ab initio calculations;electronic structure;electrical;conductivity;oxidation behavior;mechanical-properties;ti3sic2;temperature;ti3alc2;air;si
钢铁
越来越多的企业认识到共同担负环境保护职责的重要性,诸如气候变化之类的全球环境问题已经成为钢铁工业能否保持竞争力的关键因素.在过去的世纪里,钢铁企业把环境治理的重心放在末端治理上,通过减少废物排放和提高副产品的循环率来减少工业活动对环境的影响.现在则通过努力开发环境友好的生产工艺,以节约能源、减少废物排放,最终达到降低生产成本的目的.POSCO已经为完成下一代钢铁工业的技术革命作了大量的工作,包括开发全新的炼铁工艺-FINEX,由于取消了烧结和炼焦过程,FINEX可以明显降低工艺消耗和空气污染物排放.与此同时,公司继续实施节能措施和加强末端治理,在2002年,Po-hang和Gwangyang厂开始增设干熄焦设备.为了减少烧结过程的粉尘、SOx、NOx和残留有机污染物的排放,Pohang厂正在建设装备活性焦塔的废气处理设备,预计在2004年4月投入使用.通过技术上的不断突破,钢铁工业将在保持增长的同时照顾到经济和环境的同步改善.
关键词:
钢铁工业
,
环境保护
,
FINEX
,
薄带连铸
魏洪亮
,
杨晓光
,
于慧臣
材料工程
doi:10.3969/j.issn.1001-4381.2005.04.011
针对涡轮盘用GH4169合金开展了高温下单调拉伸、对称循环及非对称循环的实验工作,结果表明,该材料具有比较明显的循环软化和平均应力松弛特性.采用带Ohno/Wang修正的Chaboche粘塑性理论本构方程,对其表现出的复杂力学现象进行本构建模,介绍了Levenberg-Marquadt非线性优化算法,结合材料实验数据并通过该算法识别了本构方程参数,将本构方程通过用户子程序嵌入到有限元软件ABAQUS中,对GH4169合金的上述实验现象进行了数值模拟,计算曲线与实验曲线取得了较好的一致性.
关键词:
循环软化
,
平均应力松弛
,
本构方程
,
参数识别
Journal of Applied Physics
While the magnetic ground state associated with the step-like magnetization in Ca3Co2O6 remains to be an issue under debate, we investigate the effect of dipole dipole (D D) interaction on the magnetic ground state using the Wang-Landau algorithm. It is revealed that the D D interaction is equivalent to an effective short-range interaction term. An inclusion of this term allows a columnar-state platform and a 1/2 platform in addition to the two-step feature in the magnetization in response to magnetic field, suggesting that the role of the D D interaction in modulating the multistep magnetization in Ca3Co2O6 is non-negligible although our model may not reproduce all the experimentally observed effects. (C) 2012 American Institute of Physics. [doi:10.1063/1.3676415]
关键词:
one-dimensional ca3co2o6;density-of-states;compound ca3co2o6;algorithm;crystal
