X.H.Qu
,
J.L. Fan
,
Y.M. Li and B. Y Huang(The State Key Laboratory for Powder Metallurgy
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Central South University of Technology
,
Changsha410083
,
China)
金属学报(英文版)
The mixture of 90%W 7wt%Ni and 3wt%Fe elemental powders was milled in a planetary high-enerpy ball mill. The evolution of the structure during milling and the sintering behavior Of the milled powders were tested. The results showed that by mechanical alloying W(Ni, Fe) supersatumted solid solution with nano-meter size formed, which can enhance the sintering process. Ftilly dense alloy from the milled powders was obtained through solid state sintering. The tensile strength of the obtained alloy is over 900MPa which is comparuble to that of the alloy sintered by traditional liquid-phase sintering from un-milled powders of the same composition.
关键词:
mechanical alloying
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null
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null
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Zhenya Zhang
材料科学技术（英文）
This study investigated the microstructures and mechanical properties of ZK60 alloy prepared by a simplified rapid solidification powder metallurgy (RS P/M) processing system (S-RS P/M), which consists of warm press in dry air and hot extrusion. Microstructure characterizations showed that S-RS P/M alloy consisted of magnesium matrix and oxide stringers of ~1 μm in width. TEM (transmission electron microscopy) observations illustrated nano-size magnesia particles (10{30 nm) constituted oxide stringer in detail. Due to a relatively higher volume of nano-size magnesia particle produced during S-RS P/M process, 0.2% yield strength of S-RS P/M ZK60 alloy was found to be as high as 382 MPa, which is 10% higher than that of RS P/M alloy. The improvement in mechanical properties is mainly attributed to the combination effects of Orowan mechanism and coe±cient of thermal expansion (CTE) mismatch because of the approximately same average grain size.
关键词:
Microstructure
GUO Jin-hua
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GAO Zhen
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NI Xiao-jun
,
et al
钢铁研究学报(英文版)
Fe55Ni2Cr12Mo10B6C13Y2，Fe55Cu2Cr12Mo10B6C13Y2 and Fe55Nb2Cr12Mo10B6C13Y2 alloys with diameter of 4mm were produced by copper mold casting. The role of alloying additions (Ni, Cu or Nb) on corrosion resistance of Fe55Nb2Cr12Mo10B6C13Y2, Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 alloys were studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 alloys can be cast into bulk metallic glasses. Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 amorphous alloys with passive potential about 1500 mV exhibit good corrosion resistance in 5 % NaCl solution and 1 mol/L HCl solution. The passive current density of the alloy with Ni addition is lower than other alloys. EIS results only show one impedance element. Amorphous alloy Fe55Ni2Cr12Mo10B6C13Y2 with larger charge transfer reaction resistance indicates good corrosion resistance.
关键词:
amorphous;polarization curve;electrochemical impedance spectroscopy
Zhijian LIU
,
Zhiyou LI
,
Wei DUAN
,
Xuanhui QU
,
Baiyun HUANG
,
Siqi ZHANG
材料科学技术（英文）
A LI-B alloy has been prepared using a pretreated amorphous B powder and pure Li ingot as starting materials by continually slow addition of B powder and intensified stirring in the process of melting. The microstructure and the discharge characteristic of the materials have been investigated. Results show that the problem of temperature control in synthesis would be modified by means of continual addition of B powder, the Li7B6 would be more finery distributed in the metal Li by means of intensified stirring. The discharge characteristic of the Li-B alloy using amorphous B as starting materials is almost the same with that of using crystalline B.
关键词:
张志纯
,
龙志林
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危洪清
,
李乡安
,
彭建
,
唐平
稀有金属材料与工程
采用单辊法和铜模铸造法制备了Fe75-xMxHf3Y2B20(M=Co,Nb;x=0,4 at%)合金系的非晶薄带和非晶棒样品,并测试了该非晶合金系的差示扫描量热曲线、X射线衍射图谱和软磁性能.结果表明:少量的Nb或Co替代Fe75Hf3Y2B20中的Fe元素,合金的热稳定性和玻璃形成能力可得到明显的提高;其中Fe71Nb4Hf3Y2820的过冷液相区宽度△Tx高达75 K,约化玻璃转变温度Trg为0.58,直径达4 mm,饱和磁感应强度为0.97～1.08 T,该非晶合金同时具有较大的热稳定性、较强的玻璃形成能力和较好的软磁性能.
关键词:
铁基块体非晶合金
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过冷液相区
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玻璃形成能力
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软磁性能
Journal of Alloys and Compounds
Al85Ni5Y6Co2Fe2 fully amorphous and partially amorphous powders were prepared by nitrogen gas-atomization method. The microstructure and thermal stability as a function of powder size were investigated. A majority of the powders are below 45 Vm, and the content of amorphous phase is as high as 97.3% in the <25 mu m size range. With the increase of particle size, the phase constituent alters from amorphous to amorphous' + fcc-Al, then fec-Al + AlNiY + Al-3(Ni, Fe), and finally fcc-Al + Al9Co2 + Al3Y + Al-3(Ni, Fe). All of the powders show three exothermic reactions in the DSC traces, and the <25 mu m size range presents a wide supercooled liquid region of 22 K and a primary crystallization temperature of 580 K. The Al85Ni5Y6Co2Fe2 alloy powders exhibit a high microhardness of near 348 Hv, suggesting its good potential for structural application. (C) 2006 Elsevier B.V. All rights reserved.
关键词:
aluminum;amorphous structure;gas-atomization;microhardness;supercooled liquid region;atomic-structure;metallic-glass;alloy;powders;ni;al90fexce10-x;particles;extrusion;strengths;aluminum
陈伟荣
,
王清
,
程旭
,
张庆瑜
,
董闯
金属学报
在三元Fe-B-Y合金系中, 以团簇线判据设计了5个基础合金成分, 即5条成分线Fe8B3-Y, Fe8B2-Y, Fe83B17-Y, Fe6B-Y和Fe9B-Y与一条团簇线Fe12Y-B的交点. 在此基础上加入微量Nb和M(M=Ti, Hf, Ta, Mo, Ni和Sn)形成五元合金, 用铜模铸造方法制备出直径为3 mm的合金棒. 考虑到元素B和Y在合金制备过程中的损耗, 对每个合金进行了成分修正.在M=Ti, Hf, Ta和Mo时, 能够形成块体非晶合金的三元基础成分均接近Fe8B3-Y与Fe12Y-B两条团簇线交点成分, 表明其对应的基础团簇为Archimedes八面体反棱柱Fe8B3. 最佳非晶成分为(Fe69.9B24.6Y5.5)96Nb2Ti2,其Tg=944 K, Tx=997 K, Trg=0.666.当M=Ni和Sn时, 均没有得到块体非晶合金.
关键词:
团簇线
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Fe-based bulk metallic glass
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composition design
陈伟荣
,
王清
,
程旭
,
张庆瑜
,
董闯
金属学报
doi:10.3321/j.issn:0412-1961.2007.08.003
在三元Fe-B-Y合金系中,以团簇线判据设计了5个基础合金成分,即5条成分线Fe8B3-Y,Fe8B2-Y,Fe83B17-Y,Fe6B-Y和Fe9B-Y与一条团簇线Fe12Y-B的交点.在此基础上加入微量Nb和M(M=Ti,Hf, Ta,Mo,Ni和Sn)形成五元合金,用铜模铸造方法制备出直径为3 mm的合金棒.考虑到元素B和Y在合金制备过程中的损耗,对每个合金进行了成分修正.在M=Ti,Hf,Ta和Mo时,能够形成块体非晶合金的三元基础成分均接近Fe8B3-Y与Fe12Y-B两条团簇线交点成分,表明其对应的基础团簇为Archimedes八面体反棱柱Fe8B3.最佳非晶成分为(Fe69.9B24.6Y5.5)96Nb2Ti2,其Tg=944 K,Tx=997 K,Trg=0.666.当M=Ni和Sn时,均没有得到块体非晶合金.
关键词:
团簇线
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铁基块体非晶合金
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成分设计
Transactions of Nonferrous Metals Society of China
The surface properties of ZM5 Mg-base alloy were modified by laser cladding with Al+Y powder. Laser cladding was carried out with a 5 kW continuous wave CO2 laser by melting the preplaced powder mixture of Al and Y. Following laser cladding, the cladding zone was characterized by a detailed microstructural observation and phase analysis. Moreover, the microhardness and element distribution were evaluated in detail. The surface modified layer consists of Mg-17 Al-12 and Al-4 MgY phases, while alpha-Mg and Mg-17 Al-12 in the substrate. The microhardness of the cladding zone was significantly enhanced as high as HV122 - 180 as compared to HV60 - 80 of the substrate region. The maximal hardness about HV224 is in the interface due to the formation of intermetallic Mg-17 Al-12 phase. The microstructure is refined and Mg diffuses into the cladding material which leads to the formation of Mg-17 Al-12.
关键词:
laser cladding;ZM5 Mg base alloy;rare earth;Al plus Y powder;microstructure;magnesium;microstructures;behavior
K.M. Chang(Department of Mechanical and Aerospace Engineering
,
West Virginia University
,
P.O. Box 6160
,
Morgantown
,
WV 26506
,
USA Manuscript received 26 August 1996)
金属学报(英文版)
P/M superalloy disks obtain their final strength by appropriate heat treatments; the maximum attainable strength depends on the rapid cooling rate from the solution annealing. A rapid quench of a large disk forging can cause two problems, surface cracking and shape distortion.In the past,many attempts employ the finite element code to model and to predict temperature evolution and induced stress distribution in a large turbine disk. The major difficulty was the correct description of alloy behavior; particularly the thermomechanical properties and the failure criteria of material during the cooling. High temperature fatigue resistance is always the key requirement for disk materials. New methodology of residual life management emphasizes the initiation as well as the propagation of the cracks developed under the service conditions. One of major challenges to P/M superalloys is the time-dependent behavior of fatigue cracking, which relates to the well-known SAGBO (stress-assisted grain boundary oxidation) phenomenon.A great effort has been done to understand the micro-mechanism of time-dependent fatigue crack propagation resulted in the second generation of P/M superalloys. Further improvement on temperature capability of disk alloys at rim area may lead to the idea of dual-property disks.Different grain structures at different portions of a large disk are possible,as the property requirements for different locations are different. This goal is achievable if the thermal history at specific disk locations can be controlled to develop desirable microstructures and properties.Some suggestions on the future direction of research efforts will be discused.
关键词:
:superalloy disk
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null
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