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排序方式: 共有339条查询结果,搜索用时 312 毫秒
51.
Texture evolution in 1050 commercial purity aluminum severely deformed by equal channel angular pressing (ECAP) is investigated by electron back scattered diffraction (EBSD). Pole figures and orientation distribution function (ODF) plots are generated for samples processed to 1, 2, 4, 8, 12 and 16 passes. The processing was done using route BC, in which the samples were rotated by 90° in the same sense between subsequent pressings. Two different sized scans were performed on the flow plane of the processed samples. The orientations constituting the favorably oriented fibers are depicted and crystal orientation maps are generated. The spatial distribution of grains having these orientations are revealed through these maps. The fraction of the main texture fibers for a 5° spread around the specified orientations is experimentally calculated and a quantitative idea on the evolution of texture is presented. The results ascertained that the texture intensity around the main fibers generally weakens with number of ECAP passes. 相似文献
52.
The formation of PSB-like shear bands in cyclically deformed ultrafine grained copper processed by ECAP 总被引:1,自引:0,他引:1
S. D. Wu Z. G. Wang C. B. Jiang G. Y. Li I. V. Alexandrov R. Z. Valiev 《Scripta materialia》2003,48(12):1605-1609
Cyclic deformation was performed on ultrafine grained copper processed by ECAP. Shear bands (SBs) and adjacent microstructures were investigated using electron channeling contrast in scanning electron microscope. The possible formation mechanism of SB was discussed based on the characteristic distribution of defects introduced by ECAP. 相似文献
53.
采用碳纳米管孕育块铸造法制备多壁碳纳米管/AZ31镁基复合材料,经等径角挤压(ECAP)变形后对复合材料在3.5%NaCl(质量分数)的腐蚀介质中进行静态浸渍试验和电化学极化曲线测定,研究等径角挤压变形工艺对复合材料抗腐蚀性能的影响;利用数码相机、扫描电子显微镜对复合材料腐蚀前后的表面形貌进行观察和分析;并对复合材料的抗腐蚀机理进行分析。结果表明:等径角挤压变形工艺能有效的提高多壁碳纳米管(CNTs)/AZ31复合材料的抗腐蚀性能,经等径角挤压变形4道次后,复合材料的平均腐蚀速率由挤压态的0.6035mg/(m2·s)降为0.2963mg/(m2·s)。腐蚀电流密度Icorr由ECAP变形前的3.363μA/cm2减小到2.269μA/cm2。 相似文献
54.
采用等通道转角挤压(Equal Channel Angular Pressing, ECAP)并结合热处理制备了Ag/Ti3AlC2复合材料。通过XRD、SEM分析物相和形貌, 探讨了不同热处理条件下Ag/Ti3AlC2材料的电阻率和力学性能。结果表明: 采用ECAP可以明显致密化Ag/Ti3AlC2疏松坯体, 且在ECAP的剪切作用下, 层片状Ti3AlC2颗粒沿基面分层并按一定方向排列。Ti3AlC2的定向排列使材料性能呈现各向异性: 垂直于Ti3AlC2排列方向时, Ag/Ti3AlC2材料的电阻率和压缩强度更高。后续热处理提升了Ag/Ti3AlC2的电阻率和压缩强度, 并发现在800 ℃时增幅显著。这主要归因于Ag与Ti3AlC2在高温下明显增强的界面反应。本研究表明采用ECAP方法可以在致密化Ag/MAX复合材料的同时调控其显微组织, 而结合热处理可以进一步调控界面反应并优化材料性能。 相似文献
55.
M. Shaat 《Materials Science & Technology》2018,34(10):1149-1167
This review presents an investigation on effects of the processing conditions on the microstructural evolution and mechanical properties of commercial pure titanium processed by Equal Channel Angular Pressing (ECAP). An overview of ECAP processing is presented. A discussion on the microstructure evolution of ECAPed titanium emphasising effects of the ECAP-route type, processing temperature, number of ECAP passes, and mechanical/thermal treatments is presented. Moreover, the variations of the mechanical properties (yield strength, tensile strength, and ductility) of titanium as functions of the grain size are reported for the different conditions of ECAP processing. In addition, the best estimates of the Hall–Petch parameters for titanium processed by ECAP, ECAP followed by mechanical and/or thermal annealing are reported. 相似文献
56.
57.
58.
Y. W. Tham M. W. Fu H. H. Hng Q. X. Pei K. B. Lim 《Materials and Manufacturing Processes》2007,22(7):819-824
The experimental researches on Equal Channel Angular Extrusion (ECAE) process of commercial available Al-6061 alloy were conducted and the grain refinement after ECAE processing was investigated. Sixteen passes of ECAE processing at room temperature were conducted and the relationship of grain refinement with extrusion pass was established. The property enhancements after ECAE processing including ultimate tensile strength and Vickers microhardness were investigated to determine the effects of the number of ECAE passes on the mechanical properties of the extruded samples. The research presents a whole picture of ECAE processing of the alloy for up to 16 passes. 相似文献
59.
Xu Shubo Zhao Guoqun Wu Xin Ma Xinwu Guan Yanjin 《Frontiers of Materials Science in China》2007,1(2):187-196
Equal channel angular pressing (ECAP) has the capability of producing ultra fine-grained (UFG) materials bellow the dimension
of 1 μm. At present, it is one of the most important methods to get bulk UFG materials. Multi-pass ECAP processes for round
workpieces are investigated by using numerical simulations and experimental studies in this paper. The deformation mechanism
of ECAP for grain refinement is obtained. Three processing routes A, B and C are simulated in order to study the influence
of the processing routes to the deformation uniformity of the workpiece. The finite element (FE) analysis results of the multi-pass
ECAP process show that the different processing routes result in the different deformation distributions. The grain in the
workpiece is refined obviously after multi-pass pressing. The microstructures of the processed material are more different
than that of the microstructure of the annealing initial equiaxed grains. The microstructure evolution of the workpiece can
be changed via different processing routes. It is found that route B can get a high angle grain boundaries distribution in
the workpiece than other routes. The results of the analysis show that the process of grain refinement can be described as
a continuous dynamic recovery and recrystallization. The microstructure evolutions of the grain refinement mechanisms and
micro-structural characteristics for different multi-pass ECAP processing routes are verified by using OM (optical model)
and TEM (transmission electron microscope) analysis. In addition, the experimental microstructure results are also consistent
with FE analysis results. 相似文献
60.
ECAP工艺细化铁基形状记忆合金研究 总被引:2,自引:0,他引:2
研究等通道转角挤压(equal channel angular pressing,简称ECAP)技术细化Fe基形状记忆合金。研究结果发现,300℃下Fe-17.8Mn-4.73Si-7.80Cr-4.12Ni(wt%)第一道次挤压力为78kN,与理论计算值70.6kN接近;第二道次挤压力上升明显,达到240kN。金相观察显示挤压后的合金晶粒沿剪切方向拉长,TEM分析显示700℃退火30min后再结晶形成0.3μm左右细小晶粒,与未挤压试样相比晶粒明显细化。ECAP挤压极大的提高了材料的力学性能,屈服强度由未挤压时220MPa提高到挤压后的890MPa;挤压后退火的合金恢复率略有提高,在预变形ε=6.5%时,获得η=74%的形状恢复率。 相似文献