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Eutectic Solidification in Al-13.0%Si Alloys with Combined Addition of Strontium and Boron

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Journal of materials Science & Technology 2009年第4期25卷 437-440页

作者： Hengcheng Liao,Ke Ding,Juanjuan Bi,Min Zhang,Huipin Wang and Lei Zhao School of materials Science and Engineering,Southeast University,nanjing 211198,china jiangsu key laboratory for advanced metallic materials,nanjing 211189,china School of materials Science and Engineering Southeast University Nanjing 211198 China jiangsu key laboratory for advanced metallic materials Nanjing 211189 China

The influence of addition of boron （B） on eutectic solidification in a near-eutectic Al-13.0%Si alloy modified with strontium （Sr） was investigated using thermal analysis and macro/microstructure observation. Addition of B in the Sr-modified alloy leads to a considerable increase in nucleation temperature （TN, the minimum temperature prior to recalescence （TM） and growth temperature （To）. In the Sr-modified alloy, nucleation of eutectic might originate at the heterogeneous sites on the mold wall or in the melt near the wall, and eutectic solidification proceeds gradually towards the center, controlled by undercooling of melt. However, with addition of B in the Sr-modified alloy, undercooling required for eutectic nucleation became small, and hence eutectic solidification might occur almost simultaneously within whole casting, controlled by amount of heterogeneous sites. With excessive addition of B in the Sr-modified alloy, nucleation of eutectic grains was explosive within the whole casting and the power of Sr on eutectic solidification was completely poisoned.

关键词： Al-Si alloys Solidification Microstructure Thermal analysis

Effect of rare earth on the microstructure and mechanical properties of as-cast Cu-30Ni alloy

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Rare Metals 2009年第6期28卷 590-595页

作者： MAO Xiangyang FANG Feng JIANG Jianqing TAN Rongsheng jiangsu key laboratory of advanced metallic materials School of Materials Science and Engineering Southeast University Nanjing 211189 China

Cu-30Ni-xRE （x = 0-0.213） alloys were prepared by a metal mould casting method. The effect of RE on the microstructure and mechanical properties of the alloys was investigated using optical microscope, scanning electronic microscope with energy-dispersive spectrometer, X-ray diffraction, and mechanical test. The results show that RE has obvious effect on refining dendrite structure and grain size, as well as on purifying the melting of Cu-30Ni alloy. With the increase of RE content, the ultimate tensile strength, yield strength, and elongation increase at first and then decrease after adding RE more than 0.095 wt.%. Cu-30Ni-0.095RE alloy possesses preferable mechanical properties, i.e., the ultimate tensile strength, yield strength, and elongation are 308 MPa, 125 MPa, and 51.2%, respectively. The microstructure and mechanical properties are worsened with increasing RE content more than 0.095 wt.%. The improvement of mechanical properties of Cu-30Ni-0.095RE alloy is attributed to RE refining microstructure and purifying the matrix.

关键词： Cu-Ni alloys rare earth (RE) microstructure mechanical properties

Magnetic properties and applications of newly-developed-nanocrys-talline Fe-(72)Cu_1Nb_2V_2Si_(14)B_9 and Fe_(72)Cu_1Nb_1Mo_1V_2Si_(14)B_9 alloys

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Chinese Science Bulletin 1997年第14期42卷 1218-1222页

作者： ZHANG YanzhongShanghai Iron and Steel Research Institute, Shanghai key laboratory of metallic Functional materials, Shanghai 200940, china Shanghai key laboratory of metallic Functional materials Shanghai Iron and Steel Research Institute Shanghai China

RECENTLY, we have successfully developed new nanocrystalline Fe72Cu1 Nb2V2Sisub>14B9 and Fe72-Cu1Nb1Mo1V2Si14B9 alloys. Their cost has been reduced and their amorphous ribbons havemuch better ductillty as compared with the early-developed and typical nanocrystalline Fe73.5-Cu1Nb3Si13.5B9 and Fe73.1 Cu1.2Nb3.2Si12.5B10 alloys. The new alloys still show superiorsynthetical magnetic properties and have practically been applied to several important fields. Inthis note, we report magnetic properties for the new alloys, analysis results of core losses andseveral application examples.

关键词： nanoerystalJine alloy core loss relative permeability switching mode power supply pulser transformer.

Structure Evolution of Bulk metallic Glass Zr_(52.5)Ni_(14.6)Al_10Cu_(17.9)Ti_5 during Annealing

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Journal of materials Science & Technology 2000年第4期16卷 357-361页

作者： Guo HE, Zan BIAN and Guoliang CHEN (State key laboratory of advanced Metals and materials, University of Science and Technology Beijing,Beijing 100083, china) State key laboratory of advanced Metals and materials University of Science and Technology Beijing Beijing 100083 China

Bulk metallic glass Zr_52.5Ni_14.6Al_10Cu_17.9Ti_5 was prepared by melt injection casting method. Its glass transition and crystallization temperatures were determined by differential scanning calorimetry (DSC) to be 631 K and 710 K respectively. By analysis of X-ray diffractometry (XRD) and transmission electron microscopy (TEM ), the predominant crystallized phase of Zr_2Ni0.67O0.33 distributed on glass state matrix was detected after annealing at 673 K for 600 s. The transformation to Zr_2Ni_0.67O_0.33 and a small amount of ZrAl and Zr_2Cu took place after annealing for 600 s at temperature from 703 K to 723 K. With increasing annealing temperature from 753 K to 823 K, the amounts of ZrAl and Zr_2Cu increased, but the size of the crystals did not significantly change. The transformation to Zr_2Ni_0.67O_0.33 is interface-controlled, but is diffusion-controlled to Zr_2Cu and ZrAl. With increasing annealing temperature up to 200 K above T_x, the nanometer grains became very fine because of the increase of nucleation rate for Zr_2Cu and ZrAl.

关键词： Structure Evolution of Bulk metallic Glass Zr Ti5 during Annealing Al10Cu Ni Cu

Micro-alloying of yttrium in Zr-based bulk metallic glasses

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Progress in Natural Science:materials International 2011年第1期21卷 46-52页

作者： Wei-jie PENG,Yong ZHANG State key laboratory for advanced Metals and materials, University of Science and Technology Beijing,Beijing 100083,china State key laboratory for advanced Metals and materials University of Science and Technology Beijing Beijing 100083 China

The effect of yttrium addition on the glass-forming ability(GFA) and mechanical properties of the Zr-based (Zr0.525Al0.1Ti0.05Cu0.179Ni0.146)100-xYxand(Zr0.55Al0.15Ni0.1Cu0.2)100-xYx(x=0,0.2,0.4 0.6,1,2) alloys was ***-alloying of 0.6%yttrium enhances the room temperature ductility as well as the GFA of the Zr-based *** mechanism of enhancing the GFA and room temperature ductility was *** is indicated that proper yttrium addition stabilizes the undercooled liquid by means of forming lots of ordered clusters,thus improving the GFA and the room temperature ductility.

关键词： micro-alloying glass-forming ability Zr-based alloys yttrium

Effect of TRT process on GFA,mechanical properties and microstructure of Zr-based bulk metallic glass

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Progress in Natural Science:materials International 2011年第1期21卷 53-58页

作者： Guang-qiao LIU~1,Sheng-zhong KOU~(1,2),Chun-yan LI~1,Yan-chun ZHAO~1,Hong-li SUO~2 1.State key laboratory of Gansu advanced Non-ferrous Metal materials, Lanzhou University of Technology,Lanzhou 730050,china 2.The key laboratory of advanced Functional materials(Ministry of Education), Beijing University of Technology,Beijing 100022,china State key laboratory of Gansu advanced Non-ferrous Metal materials Lanzhou University of Technology Lanzhou 730050 China The key laboratory of advanced Functional materials (Ministry of Education) Beijing University of Technology Beijing 100022 China

Series of rod samples of Zr55Al10Ni5Cu30 alloy were prepared by magnetic suspend melting and copper mold suction casting *** effect of thermal rate treatment（TRT） process on glass forming ability（GFA）,mechanical properties and microstructure of Zr-based bulk metallic glass were *** shows that GAF,mechanical properties and microstructure of as-cast Zr55Al10Ni5Cu30 BMGs alloy to a large extent is related to TRT *** and thermal stability of as-cast Zr55Al10Ni5Cu30 alloy increase when overheating temperature *** liquid region△Txand parameterγincrease from 73 K to 89 K,from 0.413 to 0.417,respectively,when casting voltage increases from 7 kV to 10 *** a threshold overheating temperature is found for the fully amorphous structure,below which it may have an intersection with the crystallization *** is found that the compressive strength increases and the compressive plasticity slightly decreases when overheating temperature ***,the compressive strength and the compressive plasticity simultaneously increase to 1.91 MPa and 2%when casting voltage increases to 10 kV.

关键词： bulk metallic glass glass forming ability(GFA) mechanical properties thermal rate treatment(TRT) process microstructure

Microstructure of Differently Annealed NanocrystallineFe_(72.7)Cu_1Nb_(1.8)Mo_2Si_(13)B_(9.5) Alloy

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Journal of materials Science & Technology 1998年第4期14卷 327-330页

作者： YanZhong ZHANG and Huijuan JIN (Shanghai key Lab. of metallic Functional materials, Shanghai Iron and Steel Research Institute,Shanghai 200940, china) Shanghai key Lab. of metallic Functional materials Shanghai Iron and Steel Research Institute Shanghai 200940 China

The microstructure of differently annealed nanocrystalline Fe72.7Cu1Nb1.8Mo2Si13B9.5 alloy was investigated by using Mssbauer spectroscopy and transmission electron microscope. The specimens were isochronally annealed at temperatures between 480℃ and 600℃ for 0.5 h. The experimental results show that the microstructure mainly consists of the nanoscale bcc α-Fe(Si) grains and the residual amorphous matrix phase. A trace paramagnetic phase was found for annealing about above 500℃. The volume fraction of cr-Fe(Si) grain increases with increasing annealing temperature, whereas the average size of grain is almost unchanged above 480℃ up to 580℃. The calculated thickness of the intergranular layer of the residual amorphous matrix clearly decreases with increasing annealing temperature.

关键词： Mo2Si Microstructure of Differently Annealed NanocrystallineFe Si Alloy Cu1Nb

General Properties of Low-frequency Power Losses in Fe-based Nanocrystalline Soft Magnetic Alloys

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Journal of materials Science & Technology 2000年第1期16卷 37-44页

作者： Yanzhong ZHANG, Huijuan JIN and Ying SHI (Shanghai key laboratory for Research and Developing and Applications of metallic Function materials, Research Center, Shanghai Iron and Steel Research institute,Shanghai 200940, china) Shanghai key Lab. for Research and Developing and Applications of metallic Function materials Research Center Shanghai Iron and Steel Research Institute Shanghai 200940 China

The dependences of the power loss per cycle on frequency f and amplitude flux density Bm have been investigated for the three main original magnetic states in five sorts of Fe-based nanocrystalline soft magnetic alloys in the ranges of 10 Hz<=f<=1000 Hz and 0.4 T<= Bm <=1.0 T. The total loss P is decomposed into the sum of the hysteresis loss Physt, the classical eddy current loss Pel and the excess loss Pexc. Physt has been found to be proportional to Bm^2 and f. The behavior of Pexc/f vs f being equivalent to P/f vs f clearly exhibits nonlinearity in the range not more than about 120 Hz, whereas the behavior of P/f vs f roughly shows linearity in the range far above 100 Hz and not more than 1000 Hz. In the range up to 1000 Hz, Physt is dominant in the original high permeability state and the state of low residual flux density, whereas Pexc in the state of high residual flux density is dominant in the wider range above about 100 Hz. The framework of the statistical theory of power loss has been used for representing the behavior of Pexc/f vs f. It has been found that the number n of the simultaneously active 'Magnetic Objects' linearly varies as n = n0 + Hexc/H0 as a function of the dynamic field Hexc in the range below about 120 Hz, whereas n approximately follows a law of the form n = n0 + (Hexc/H0)^m with 1 < m < 2 in the range far above 100 Hz and not more than 1000 Hz. The values of the field HO in principle related to the microstructure and the domain structure have been calculated for the three states.

关键词： General Properties of Low-frequency Power Losses in Fe-based Nanocrystalline Soft Magnetic Alloys Fe

Effects of cooling rates on the mechanical properties of a Ti-based bulk metallic glass

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Science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 394-398页

作者： XIAO YueHua, WU Yuan, LIU ZhiYuan, WU HongHui & Lü ZhaoPing State key laboratory for advanced Metals and materials, University of Science and Technology Beijing, Beijing 100083, china State key laboratory for advanced Metals and materials University of Science and Technology Beijing Beijing China

Mechanical properties of the glassy specimens fabricated at different cooling rates with a composition of Ti40Zr25Cu12Ni3Be20 were systematically investigated. It was confirmed that faster cooling rates caused not only a larger amount of frozen-in free volume but also a higher glass transition temperature in the bulk glassy alloy. Increase in the free volume was found to favor plastic deformation and then to give rise to larger compressive plasticity, whilst the rise in the glass transition temperature seemed to be closely related to the higher yield strength. Moreover, the increase of yield strength and plasticity induced by fast cooling rates may also be associated with the residual stress generated during the fabrication process. Our results suggest that the deformation behavior of bulk metallic glasses is sensitive to various factors and influences from the other factors should be excluded as far as cooling-rate effects on bulk metallic glasses are considered.

关键词： bulk metallic glasses mechanical properties cooling-rate effects residual stress