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研究了温度及应变速率对Ti-24Al-14Nb-3V-0.5Mo(at-%)合金超塑性能的影响。试验结果表明,在980℃,3.5×10^-^4s^-^1的最佳超塑变形条件下,合金显示出较高的超塑性;应变速率敏感性指数m为0.69,拉伸延伸率El.为818%。根据其细小的α2+β0两相组织和等温拉伸的试验方法,确定合金的超塑性属于细晶组织超塑性。在超塑变形过程中,合金无空洞产生,显微组织发生动态粗化 相似文献
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Ti-24Al-14Nb-3V-0.5Mo合金的超塑性 总被引:2,自引:0,他引:2
研究了温度及应变速率对Ti-24Al-14Nb-3V-0.5Mo(at.-%)合金超塑性能的影响.试验结果表明,在980℃,3.5×10~(-4)s~(-1)的最佳超塑变形条件下,合金显示出较高的超塑性;应变速率敏感性指数m为0.69,拉伸延伸率El.为818%.根据其细小的α_2+β_0两相组织和等温拉伸的试验方法,确定合金的超塑性属于细晶组织超塑性.在超塑变形过程中,合金无空洞产生,显微组织发生动态粗化. 相似文献
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此简要地叙述了工业性试生产Zn-Al22超塑性管材的工艺流程。采用慢速等液面浇注法和几次均匀化处理实现晶粒细化。在ε=2×10^-2S^-1的应变速率下反挤压φ49×2.25×250mm管材1200只,超塑性能最高值δ=1620%,流变应力σb=2.36MPa. 相似文献
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大晶粒含钛Fe-36.5Al基合金的超塑性研究 总被引:2,自引:0,他引:2
通过对未加Ti及加有不同量Ti的Fe-36.5Al(原子分数,%)基合金的高温变形行为的研究,发现加Ti的合金在900—1000℃,初始应变速率为2.08×10 ̄(-4)-8.33×10 ̄(-2)s ̄(-1)范围内比未加Ti的FeAl合金的延伸率有较大幅度提高,且应变速率敏感性指数m值普遍超过0.3。随含Ti量的增加,m值及延伸率也普遍提高,最高值分别达到0.43和297%.金相及TEM分析表明,变形过程中出现了明显的晶粒细化及亚晶形成过程,并由此导致了大晶粒含钛FeAl基合金的超塑性。 相似文献
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超细晶粒金属材料 (晶粒粒径 <10 μm)通常都具有很高的拉伸延性 (超塑性 )。准单相合金在较低应变速率 (<10 - 3s- 1)和大约 0 8Tm(合金熔点 )的温度下可显示超塑性。对镁基合金的高应变速率超塑性进行了广泛的研究 ,在高温 (~ 6 2 3K)下也表现出高应变速率超塑性。降低变形温度 ,有利于减少能量消耗、减轻表面氧化并防止合金元素的选择贫化。有关镁基复合材料的低温超塑性行为的研究 ,至今几乎没有报道 ,因此 ,日本的大阪城市技术研究所研究了镁基复合材料的低温超塑性行为。研究用的材料是用 17% (体积 )SiC颗粒增强的ZK6 0… 相似文献
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AlN/Mg┐5%Al合金基复合材料镁基复合材料由于密度小,力学、物理和热性能优良,所以在汽车和航天工业中有其很大的应用潜力。镁基复合材料因为在高的应变速率,(0.1~10s-1下具有250%~600%延伸率的超塑性,故可望利用近终成形方法加工成形。... 相似文献
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X. J. Xu W. Wang L. CaiJiangsuUniversity of Science Technology Zhenjiang China 《金属学报(英文版)》2002,15(5):425-430
The superplastic characteristics of the β-SiC whisker reinforced 2024 aluminum composite, fabricated by pressure infiltration and hot-rolling after extrusion, were investigated. The composite has a fine grain size of about 1μm, and exhibits a maximum tensile elongation of 370% in the initial strain rate of 3.3×10-3s-1 at 788K.The superplastic deformation mechanism of the composite is thought to be grain boundary (interface) sliding accommodated by grain boundary diffusion of aluminum atom and an appropriate amount of liquid phase. 相似文献
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HIGH STRAIN RATE SUPERPLASTICITY IN A SiC_w/2024Al COMPOSITE MADE BY SQUEEZE CASTING 总被引:2,自引:0,他引:2
1.IntroductionHighStrainratesuperplasticity(HSRS)infineceramicwhiskerorparticulatereinforcedaluIninUIncompositesisveryattractipeforcommercialaPplicationsbecausetheHSRScompositesusuallyeallibitatotalelongation0f25M00%atahighstrainrate0f>10-2s-1Il-7]andoneofcurrentdrawbacksinsuperPlasticformingteclm0logyisaslowf0rIIilngratewhichistypically10-5-10-3s-1.Forindustrialfabricati0nofceramicwhiskerreinforcedaJumintuncomposites,squeezec88tingprocedureismorecost-ethetivethanpowdermetallurgy(P/M)m… 相似文献
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变形态Mg-Nd合金的组织转变和拉伸性能特征 总被引:4,自引:0,他引:4
研究不同变形条件对Mg-2.2Nd-0.5Zn-0.5Zr合金室温拉伸性能和组织的影响.经过不同条件的热挤压变形后,该合金的强度和延性都有不同程度的增加,屈强比从0.58提高到0.87左右.固定变形温度时,强度随变形速率增大而降低,延性反之.固定变形速率时,升高变形温度则强度降低,延性增加.弥散于晶界的Mg9Nd化合物细化了晶粒.变形态Mg-Nd合金的高温超塑拉伸研究发现,375℃是该合金的最佳超塑变形温度,应变速率在1×10-2s-1时,延伸率达到329%;当变形速率提高到2×10-2s-1时,该合金的延伸率仍可达到213%.分析不同真应变下的组织发现,在变形初期发生动态再结晶,晶粒得到破碎而变得细小,随着变形程度的增加,晶粒长大程度较小.在变形后的断口形貌中发现,Mg-Nd合金的超塑变形机制为晶界滑移控制下的孔洞连接协调机制. 相似文献
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《Acta Materialia》2003,51(11):3073-3084
A new processing procedure was applied to a cast Mg-9% Al alloy. This procedure involves the sequential application of extrusion and equal-channel angular pressing and is designated EX-ECAP. Experiments show that the Mg-9% Al alloy has an initial grain size of ~50 μm after casting but this is reduced to ~12 μm after extrusion and it is further reduced to ~0.7 μm when the extruded alloy is subjected to ECAP for 2 passes at 473 K. Although the cast alloy exhibits extremely limited ductility and the extruded alloy is only moderately ductile, it is demonstrated that processing by EX-ECAP produces excellent superplastic ductilities including the occurrence of both low temperature superplasticity and high strain rate superplasticity. The EX-ECAP process is less effective when the ECAP step is conducted at 573 K because, although the pressing is then very easy, there is significant grain growth at this higher temperature. 相似文献
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1 INTRODUCTIONMetalmatrixcompositesareattractiveformanystructuralapplicationsbecauseoftheirhighspecificstrengthandtheirmodulusofelasticity .Formetalmatrixcompositescontainingceramicreinforcements ,stressconcentrationduringtensiledeformationoccursatinte… 相似文献
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通过2道次往复挤压制备细晶ZK60合金,在443~523K和初始应变速率为3.310-4~3.310-2s-1的范围内测试合金的低温超塑性。结果表明:往复挤压ZK60合金的平均晶粒尺寸约为5.0m,分布于基体内的破碎二次相颗粒和沉淀颗粒尺寸分别为不大于175nm和50nm。该合金具有低温准超塑性,在523K和3.310-4s-1应变速率下伸长率最大,为270%;在443和473K时,应变速率敏感系数m小于0.2;在523K时m为0.42。当温度不高于473K和523K时,超塑性变形激活能分别不高于63.2kJ/mol和110.6kJ/mol。当低于473K时,主要的超塑性流变机制为晶内滑移;在523K时,主要的超塑性变形机制为晶界滑移,由晶界扩散控制的位错蠕变为主要的兼容机制。 相似文献
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The mechanical Properties of some alloys canbe improved When ultrafine microstrUcttires areobtained. Some materials appear some unusualproperties [l, 2] when grain sizes reach aboutnanoscale. Theoretic analysis and experimentalresults on superplasticity show that the ultrafinegrain (submicron or nanoscale grains, subgrainsor nanophase etc.) materials are possible to exhibit superplaSticity under much lower temperatllTe, or their superplastic strain rate can be enhanced to great extent [3--5]… 相似文献
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T. Imai L. Geng J. F. Mao I. Tochigi ) National Industrial Research Institute of Nagoya - Hirate-cho Kita-ku Nagoya - Japan ) School of Materials Science & Engineering Harbin Institute of Technology Harbin China ) Kanagawa High-Technology Foundation Kanagawa Science Park -- Sakado Takatsu-ku Kawasaki Kanagawa Japan 《金属学报(英文版)》2000,13(2):581-586
1.IntroductionHighstrainratesuperplasticity(HSRS)inceramicwhiskerorparticulatereinforcedaluminumalloycompositesisexpectedtoofferanefficientlynearannetshapeformingtech-niquetoautomobile,aerospace,andevensemi--conductorindustries,sincetheHSRScom-positesusuallyexhibitatotalelongationof250--600%atahighstrainrateofabout0.1--10s~1[1-ill.ItisthoughtthatprimarydeformationmechanismoftheHSRSisgrainboundaryslidingsincethecompositeshavethefinegrainsizeof3--0.8pm.TheHSRSofthecompositesusuallymanifest… 相似文献