D. Ferguon
,
W. N. Chen and H. Ferguson (Dynamic Systems Inc. Poestenkill
,
NY 12140
,
USA)
金属学报(英文版)
Ultrafine grain size is often achieved by severe plastic deformation. A few techniques have been devel- oped to achieve severe plastic deformation,such as equal channel angular (ECA ) processing, torsion, and accumulative roll bonding (ARB) techmpues. This paper will introduce a moftiaxis deformation technique which can achieve essentially unlimited strain with constant deformation volume. The mul- tiaxis deformation can be fully restrained or unrestrained.The bulk volume of a multiaxis restraint compression specimen can be easily machined into mechanical testing specimens for mechanical property measurement and other studies.
关键词:
ultrafine grain
,
null
,
null
W. Chen
,
D. Fergson and H. Ferguson (Dynamic Systems Inc. Poestenkill
,
NY 12140
,
USA)
金属学报(英文版)
There is a considerable interest in developing methods for processing of materials with ultrafine grain si- zes. Widely used methods in refining microstructure are severe/intense plastic deformation techniques, such as torsion straining, equal channel angular (ECA) pressing/extrusion,and accumulative roll bonding (ARB) technique.While the torsion technique has been available for decades,a new torsion system has been developed at DSI for simulation of complex stress states such as combination of shear and compression or shear and tension stress states. The equal channel angular pressing technique is ma- inly used for production of ultrafine grain aluminum alloys,which is aimed at develoment of high strain rate superplasticity.The accumulative roll bonding technique has been applied for the rolling of both aluminum alloy and steels to produce ultrafine gained materials. Three different types of hot compression deformation methods, each with a different number of deforma- tion axis, are introduced in this paper. They are single axis deformation, two axis deformation and three axis deformation.The single axis deformation has us or little restraint such as plane strain type testing and axisymmetric compression testing, the two - axis deformation can be fully restrained or un- restrained, and the three - axis deformation has no restraint. The two - axis restrainsd compression deformation techopue is recommended for loboratory side after comparing the single - axis and the three - axis deformation techniques since the bulk volume of the two - axis restraint compression speci- men can be easily machined into mechanical testing speciments for mechanical property measurement and other studies,and the technique can be aplied to studies of any metallic materials.
关键词:
ultrafine grain
,
null
王夫成
,
詹马骥
,
郎经纬
,
王若民
,
陈国宏
,
杜晓东
表面技术
doi:10.16490/j.cnki.issn.1001-3660.2015.09.019
目的：研究老旧高压输电耐张线夹内部交流腐蚀。方法截取已运行35 a的耐张线夹并解剖,采用扫描电子显微镜分析腐蚀区的微观形貌,采用X 射线衍射仪、能谱仪和X射线光电子能谱仪对腐蚀区元素及物相进行分析鉴定,分析线夹内部腐蚀损伤演化过程。结果线夹内表面与铝线表面局部出现大量白色腐蚀产物和黑色覆盖物,白色腐蚀物呈粉末和片层两种形态。分析表明,腐蚀产物相组成为Al2 O3,AlO( OH)和AlOOH；黑色覆盖物随深度增加而减少,黑色区域主要元素为Al,O和C,物相组成为Al2 O3,C( graphite)和含C有机物。钢芯锌层破坏区的内层铝线更易腐蚀,腐蚀区呈灰黑色,微观形貌为富铁元素颗粒镶嵌在其它腐蚀产物中,区域的主要元素为Al,C,O,Fe和Zn,Fe元素存在形式为Fe2 O3；钢芯表面镀锌层局部腐蚀严重,呈现平面型点蚀形貌,主要元素为Zn,Al,C和O,Zn腐蚀产物为六边纤锌矿结构ZnO。结论内部交流腐蚀原因为液体渗入,同时腐蚀产生大量的热致使材料分解。
关键词:
耐张线夹
,
交流腐蚀
,
点蚀
,
微观形貌
,
腐蚀产物
,
热分解
N.H.March
材料科学技术（英文）
A condition for local moment formation in metals derived by Stoddart and March (Ann. Phys. NY 1972 64, 174) is first used to discuss the ferromagnetism of body-centred-cubic Fe. A less detailed discussion is also added on Ni and Co. This leads into a treatment of the nonlinear response of such 3d ferromagnets to dilute substitutional impurities. Antiferromagnets responding to local changes in the exchange field caused by such impurities are also studied, Mn in Cr being one such system discussed. The paper concludes with a brief summary of clusters of transition metal atoms, with most attention devoted to Cr and to Mn.
关键词:
Journal of Applied Physics
The structure and magnetic properties of Nd2Fe14BNdelta-based alloys prepared by mechanical alloying have been investigated. For the Nd14Fe78B8Ny series, a large amount of NdN, alpha-Fe, and a small Nd2Fe14B phase are observed in x-ray diffraction patterns. With increasing Nd content, the amount of the Nd2Fe14BNdelta phase increases and alpha-Fe decreases gradually. When x greater than or equal to 25 in the NdxFe92-xB8Ny systems, some amount of the N-containing, Nd-rich phase appears. Meanwhile, the content of the nitrogen in the Nd2Fe14BNdelta phase decreases and, correspondingly, the Curie temperature decreases. The coercivity and the maximum magnetic energy product of this series attain maxima at x=25. A coercivity as high as 20 kOe has been achieved. The effect of nitrogen on the formation, composition, and magnetic properties of the Nd2Fe14BNdelta compound is discussed. (C) 2000 American Institute of Physics. [S0021-8979(00)22208-1].
关键词:
phase;sm
Xinguo ZHAO
,
Zhidong ZHANG
,
Zhijun GUO
,
Wei LIU
,
Dianyu GENG
,
Baozhi CUI
材料科学技术（英文）
The alloy with nominal composition Sm-2(Fe0.94Ti0.06)(l7) is prepared by are-melting, hydrogenation and nitrogenation processes. The Sm-2(Fe0.94Ti0.06)(17) alloy has a single phase of Sm-3(Fe, Ti)(29) with the Nd-3(Fe, Ti)(29)-type structure. The corresponding hydride phase with the same phase structure of the parent alloy was formed after a hydrogen decrepitation (HD) process at 300 degrees C. The hydrogenation at 800 degrees C mainly shows a HDDR process. The HD and nitrogenation at 500 degrees C result in increasing the Curie temperature of the alloy by 72 degrees C and by 158 degrees C due to lattice expansions, respectively. The anisotropic and isotropic Sm-3(Fe, Ti)(29)Ny magnets are obtained after HD, HDDR and the consequent nitrogenation, respectively. The optimum magnetic properties of Sm-3(Fe, Ti)(29)Ny powders achieved in the above two processes are: (i) B-r=0.82 T, H-i(c)=4.48 kA/cm, (BH)(max)=54.3 kJ/m(3), (ii) B-r=0.68 T, H-i(c)=8.14 kA/cm, (BH)(max)=66.4 kJ/m(3).
关键词:
Journal of Magnetism and Magnetic Materials
Sm1-xFe7+x (0 less than or equal to x less than or equal to 0.9) alloys were induction-melted and rapidly quenched at various wheel velocities of 20-50 m/s. The results of X-ray diffraction show that for the composition of 0 less than or equal to x less than or equal to 0.1 the rhombohedral Th2Zn17-type structure is the main phase, and for the composition of 0.2 less than or equal to x less than or equal to 0.9 the hexagonal TbCu7-type structure is formed. AC initial susceptibility experiments indicate that at annealing temperatures below 580 degrees C the amorphous phase is crystallized to the TbCu7-type phase, while annealing up to 800 degrees C the TbCu7-type phase is transformed to the Th2Zn17 phase. After nitrogenation, the optimal condition for the best magnetic properties is obtained in Sm12.5Fe87.5Ny, quenched at 50 m/s and annealed at 700 degrees C for 30 min, and consequently nitrogenated at 460 degrees C for 4 h. The best result for the coercivity H-i(c) of the Sm12.5Fe87.5Ny achieved is 18.9 kA/cm (23.7 kOe).
关键词:
quenching;Sm1-xFe7+x (O<=x<=0.9) alloys;Th2Zn17-type structure;TbCu7-type structure;nitrogenation;earth intermetallic compounds;sm-fe-n
材料科学技术（英文）
The alloy with nominal composition Sm-2(Fe0.94Ti0.06)(l7) is prepared by are-melting, hydrogenation and nitrogenation processes. The Sm-2(Fe0.94Ti0.06)(17) alloy has a single phase of Sm-3(Fe, Ti)(29) with the Nd-3(Fe, Ti)(29)-type structure. The corresponding hydride phase with the same phase structure of the parent alloy was formed after a hydrogen decrepitation (HD) process at 300 degrees C. The hydrogenation at 800 degrees C mainly shows a HDDR process. The HD and nitrogenation at 500 degrees C result in increasing the Curie temperature of the alloy by 72 degrees C and by 158 degrees C due to lattice expansions, respectively. The anisotropic and isotropic Sm-3(Fe, Ti)(29)Ny magnets are obtained after HD, HDDR and the consequent nitrogenation, respectively. The optimum magnetic properties of Sm-3(Fe, Ti)(29)Ny powders achieved in the above two processes are: (i) B-r=0.82 T, H-i(c)=4.48 kA/cm, (BH)(max)=54.3 kJ/m(3); (ii) B-r=0.68 T, H-i(c)=8.14 kA/cm, (BH)(max)=66.4 kJ/m(3).
关键词:
sm
