杨义李阁平吴松全李玉兰杨柯
材料研究学报
Gum Metal特指一类符合某些特定电子状态参数和成分条件的钛合金, 具有很多特异的性能, 如室温超塑性、低加工硬化率, 经历超过90%的冷旋锻后具有高强度、非线性超弹性、低的杨氏模量, 以及Invar和Elinvar性能等。自Gum Metal问世以来, 其特异性能的机理和变形机制便一直存在很大的争议。本文结合作者近几年的研究工作, 从合金设计、制备工艺、性能、成分敏感性和塑性变形行为等几个方面, 综合评述了该类合金的研究现状。
关键词:
金属材料
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alloy design
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composition
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preparation process
,
deformation mechanism
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null
王书晗刘振宇张维娜王国栋
金属学报
通过控温拉伸实验分析了在298, 373, 473和673 K温度下变形时, TWIP钢(Fe--25Mn--3Si--3Al)力学性能和显微组织的变化规律. 结果表明, TWIP钢的强度和延伸率均随温度的升高而降低. 通过热力学公式对不同温度下TWIP钢层错能$\it\Gamma$的估算可以推断, 温度T≥673 K时, Γ≥76 mJ/m2, 滑移为TWIP钢主要的变形机制; 298 K≤ T≤373 K时, 21 mJ/m2≤Γ≤34 mJ/m2, 孪生为TWIP钢主要的变形方式, 此时产生“TWIP”效应, 可获得较高的加工硬化速率, 从而获得高强度及高塑性.
关键词:
形变孪晶
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high temperature deformation
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deformation mechanism
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stacking fault energy
王全柱
,
张迎元
材料开发与应用
对采用熔体发泡法制造的不同密度泡沫铝进行了准静态压缩试验、拉伸试验和弯曲试验.结果表明,泡沫铝的压缩特性曲线包括线弹性变形区、平台区和密实化区.试样的高宽比H/D明显影响压缩应力-应变曲线.当H/D较小时,平台应力曲线较平滑;当H/D较大时,平台应力曲线剧烈波动,呈显著的锯齿状.且在试样中间部位出现与加载轴线呈25°-45°的剪切带.拉伸和弯曲过程中,泡沫铝应力快速增加,当达到应力峰值即屈服点后急剧减小,在最终破断失效前,没有明显的屈服变形带.压缩坪应力Rp1、拉伸屈服应力RUTS和冷弯屈服应力Rf随密度的增加而增加.
关键词:
泡沫铝
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压缩
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拉伸
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冷弯
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变形机制
许峰
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张喜燕
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程佑铭
稀有金属材料与工程
利用动态塑性变形(DPD)和准静态压缩变形(QSC)技术对纯钛圆柱样品进行对比压缩试验,研究了不同应变速率下纯钛形变孪晶和微结构演变.结果发现:2种变形方式的变形机制相似,低应变时以形变孪生为主,孪生饱和后转变为位错滑移主导;高应变速率促进了形变孪晶的产生,激发{1124}压缩孪晶的形成,同时使变形机制转变临界应变提前至0.2;纯钛在高应变速率和高应变(ε≥0.6)下出现绝热剪切带(ASB).
关键词:
应变速率
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纯钛
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变形机制
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形变孪晶
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绝热剪切带
王翔
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宋立新
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曲淼
,
任亮
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张明耀
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张会轩
高分子材料科学与工程
采用双螺杆挤出机将甲基丙烯酸缩水甘油酯(GMA)同时接枝到乙烯-辛烯共聚物(POE)和线性低密度聚乙烯LLDPE上,而后将接枝产物与聚对苯二甲酸丁二醇酯(PBT)反应性共混,通过改变POE/LLDPE比例确立了PBT/(POE/LLDPE)-g-GMA共混物分散相的最佳组成.以此为基础考察了GMA加入量对共混物的力学性能、流变行为及相形态的影响,并对共混物的形变机理进行了研究.实验结果表明,POE/LLDPE比例为50/50时冲击强度最大,在此组成下共混物的冲击强度随着GMA加入量的增加而呈现先增大后减小的趋势,并在GMA加入量(GMA/(POE+LLDPE))为5％时达到最大值;体系黏度随GMA加入量的增加而增大,过量的GMA会导致严重的交联,不利于分散相的分散,从而降低了增韧效率;橡胶粒子的空洞化促使基体发生剪切屈服是其主要的形变机理,LLDPE的引入能促进PBT发生进一步形变,从而提高增韧效率.
关键词:
PBT/(POE/LLDPE)-g-GMA
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接枝
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反应共混
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冲击强度
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形变机理
W. H. Tian
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S.L. Hu and M. Nemoto(Department of Materials Physics
,
University of Science and Technology Beijing
,
Beijing 100083
,
China)(Department of Materials Forming
,
University of Science and Technology Beijing
,
Beijing 100083
,
China)(Department of Materials Science and Engineering
,
Faculty of Engineering
,
Kyushu University
,
Fukuoka 812
,
Japan)
金属学报(英文版)
The Co3 Ti phase hardens appreciably by the fine precipitation of disordered fcc Co-rich phase upon aging after quenching from solution annealing temperature. Transmission electron microscope (TEM)observations revealed that the precipitates are platelet in shape, lying nearly parallel to the {100} planes of the L12-ordered matrix, and perfectly coherent with the matrix lattice at the beginning of aging. The high temperature strength increases appreciably with the fine precipitation of disondered Co-rich phase over the whole temperature range investigated. TEM observations of the deformed alloys after underaging revealed that saperdislocations are pinned by precipitates indicating an attractive interaction between dislocations and precipitates.
关键词:
Co_3 Ti
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null
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null
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null
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null
Y. Q. Zhao
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L. Zhou and J. Deng (Northwest Institute for Nonferrous Metal Research
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P. O. Box 51 Xi' an
,
Shaanxi 710016
,
China)
金属学报(英文版)
Ti - 40 alloy is a single β phase burn resistant titanium alloy.Its high temperature deformation mech- anism is studied and its stress - strain curves are examined he use of Gleeble - 1500 thermal -simulator. The results reveal that there are abrupt flow stress drops followed b steady state.The magnitude of the flow stress drop increases with strain rote and decreases with temperature.Deformation activation energy, Q, is 247. 5 KJ/mol. The deformation mechanism of Ti - 40 alloy is controlled by the lattice diffusion Its constitutive equation is set up, i. e.
关键词:
burn resistant titanium alloy
,
null
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null
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null
W.H. Tian
,
S.L. Hu and M. Nemoto(1) Department of Materials Physics
,
University of Science and Technology Beijing
,
Beijing 100083
,
China 2) Department of Materials Forming
,
University of Science and Technology Beijing
,
Beijing 100083
,
China 3) Department of Materials Science and Engineering
,
Faculty of Engineering
,
Kyushu University
,
Fukuoka 812
,
Japan)Manuscript received in revised form 12 October 1998
金属学报(英文版)
The effect of Cr addition on the microstructures and mechanical properties of NiAl inermetallic alloys containing 4 to 8 mol% Cr has been characterized. It is shown that Cr is not only an efficient soild solution strengthener in NiAl, it is also an efficient precipitation Strengthener by fine dispersion of α-Cr particles. Transmission electron microscope observations have revealed that fine spherical particles of α-Cr appeared homogeneously in the NiAl matrix by aging at temperatures around 1073K after solution annealing at 1563K. The aging behavior was investigated by microhardness measurements and the temperature dependence of the yield stress of NiAl containing α-Cr particles was investigated by compression tests over the tempemture range from 298 to 1173K. NiAl alloys happened appreciably by the precipitation of α-Cr particles.Dislocations bypass the particles during deformation and typical Orowan loops were observed surrounding the α-Cr particles after deformation. Although the dispersion Of α-Cr particles increases the yield strength of NiAl at intermediate temperutre, the strength decreases appreciably at higher temperatures.
关键词:
NiAl
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null
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null
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null
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null
