共查询到19条相似文献,搜索用时 171 毫秒
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采用碳纳米管孕育块铸造法制备了碳纳米管/AZ31镁基复合材料,并对其进行了等径角挤压实验.利用光学金相显微镜对它的显微组织进行了观察和分析,研究了等径角挤压变形工艺对复合材料显微组织的影响规律.结果表明:等径角挤压工艺可明显细化复合材料的晶粒组织;随着变形道次的增加,复合材料平均晶粒尺寸不断得到细化,组织更加均匀. 相似文献
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AZ31镁合金的热模拟和挤压 总被引:2,自引:2,他引:0
采用Gleeble-1500D材料热模拟实验机、630T挤压机和金相显微镜研究了在塑性变形中挤压变形对AZ31镁合金管材微观组织的影响规律,在挤压之前对镁合金铸锭进行了均匀化处理.研究结果表明:AZ31镁合金热挤压时发生了动态再结晶,材料组织比铸态时细化;随挤压比的增大,晶粒细化程度增加,平均晶粒尺寸为19~37μm. 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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By means of equal channel angular extrusion (ECAE) test, upsetting test and metalloseope, reheating mierostruetures of raw casting ingots, materials prepared by SIMA and materials extruded by ECAE in semi-solid state were investigated. The results show that compared with those of raw casting ingots and materials prepared by SIMA, reheating microstrueture of materials extruded by ECAE is the best and the final grain size is the finest. With increasing holding time, a growing phenomenon occurs in reheating microstrueture of materials extruded by ECAE, which can be described by Ostwald ripening law. The average grain size increases firstly, subsequently decreases and the shape factor of grains approaches to 1 as the reheating temperature increases. With increasing equivalent strain, the average grain size decreases. This demonstrates that reheating material extruded by ECAE technology is a good method to prepare AZ91D magnesium alloy semi-solid billets. 相似文献
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综述了切削法制备超细晶材料时加工参数和工艺条件对晶粒细化的影响,分析了切削法制备超细晶材料的力学性能、耐腐蚀性能和热稳定性等,探讨了超声振动复合切削法制备超细晶材料的可能性。在超声振动加工中,材料受低应力高速、高频撞击的影响,会发生严重的塑性变形,表面大尺寸的晶粒得到细化,同时超声振动还可以在材料表面形成表面微结构,进一步改善材料性能。因而提出将切削法和超声振动相复合,高效制备具有功能微结构的超细晶材料,为微型零件超细晶材料制备提供新的工艺选择以及理论和技术支撑。 相似文献
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The microstructure and hardness of a 2024 aluminum alloy subjected to multi-pass upsetting extrusion at ambient temperature were studied. Experimental results indicated that with the number of upsetting extrusion passes increasing, the grains of the alloy are gradually refined and the hardness increases correspondingly. After ten passes of upsetting extrusion processing, the grain size decreases to less than 200 nm in diameter and the sample maintains its original shape, while the hardness is double owing to equal-axial ultrafine grains and work hardening effect caused by large plastic deformation. 相似文献
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This study revealed that the extrusion temperature has a great influence on microstructure and mechanical properties of the Mg97Y2Zn1 alloy. The average grain sizes increased from 3 μm to 8 μm with increasing extrusion temperatures from 623K to 773 K. Both dynamic recrystallization (DRX) and static recrystallization (SRX), which occur during and after deformation, respectively, were observed. The alloy, which extruded at a relatively high temperature, exhibited lower strength because the strain strengthening was balanced by the softening that originated from DRX. Three types of morphologies, namely, big recrystallized grains, fine recrystallized grains, and non-recrystallized grains, were observed in the extruded microstructures obtained at 623 K. The dislocation density was quite high in the fully recrystallized grain. The extruded microstructures obtained at 773 K were composed of large grains with more uniform size. Their degree of recrystallization was higher and the dislocation density also declined. All dislocation in the grain were distinguished as 〈c+a〉 dislocations. Submicron scale precipitates were distributed along the newly formed recrystallized grain boundaries and had a remarkable pinning effect on the recrystallized grain growth after extrusion at 773 K. The precipitates can be divided into two main types: mixed type and single type. 相似文献
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挤压铸造铝基复合材料的高应变速率超塑性 总被引:3,自引:0,他引:3
用挤压铸造、挤压比仅为10∶1的挤压以及进一步的轧制成功地制备了具有高应变速率超塑性行为的βSiC晶须增强LY12复合材料。该复合材料晶粒细小,约为2μm;在温度为803K和初始应变速率为1.1×10-1s-1时,延伸率达350%,应变速率敏感系数m值约为0.35;超塑性变形的主要机制是细小晶粒的晶界滑动,适当的微量液相有利于该复合材料的高应变速率超塑性。 相似文献
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挤压速度和电磁铸造锭坯对AZ31镁合金板材组织和性能影响 总被引:1,自引:0,他引:1
文章研究挤压条件下挤压速度和电磁铸造锭坯对挤压态AZ31镁合金板材组织和性能的影响。研究结果发现,挤压速度比较低时,板材晶粒尺寸小,板材的表面质量比较好;随着挤压速度的降低,抗拉强度、屈服强度和延伸率都有一定的提高。由于镁合金是HCP的晶体结构,同时对挤压速度非常敏感,对变形均匀性影响比较大,因此造成挤压板材的内外晶粒大小不均。在电磁场的作用下,溶质在晶内的固溶度增大,同时晶粒大小也比常规铸造的细小,因此电磁铸造的锭坯经挤压机挤压后,挤压板材的晶粒尺寸比较细小,且强度和塑性都有所提高。 相似文献
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Ying Zhao Baoyun Song Jiuyang Pei Chunbo Jia Bing Li Guo Linlin 《Journal of Materials Processing Technology》2013,213(11):1855-1863
Experiments and numerical simulations were conducted to analyze the continuous extrusion of AA6063 aluminum alloy under extrusion wheel angular velocities of 0.52, 0.78, 1.04 and 1.3 rad/s. Simulation results indicate that variations in extrusion wheel velocity directly affect material deformation and significantly influence the maximum extrusion temperature. This work also reveals that deformation and temperature have opposing effects on the microstructure of the resulting product. A greater wheel velocity causes a higher strain rate and extrusion temperature. Increasing the wheel velocity, at an initially low speed, causes a large increase in strain rate. This results in a decrease in grain size. In contrast, at high wheel velocities, further increases to wheel velocity have much less effect on the strain rate, leading to an increase in grain size as the increased extrusion temperature dominates the mechanics of grain growth. Tensile test results demonstrate that the tensile strength of the resulting aluminum extrusions mainly depends on the exit temperature, which is decided by the deformation speed. Tensile strength and hardness slightly increase with increased deformation speed. Extremely high extrusion temperature results in brittle failure and low mechanical properties of the resulting product when the extrusion speed reaches 1.3 rad/s. This paper suggests that an optimum extrusion wheel velocity, which will generate products with good mechanical properties, exists. 相似文献