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1.
2.
On the mechanical behavior of aluminum alloys reinforced by long or short alumina fibers or SiC whiskers 总被引:2,自引:0,他引:2
This study was initiated to examine the dispersion of longitudinal and transverse waves in metal matrix composites in order to obtain the dynamic elastic modulus and to evaluate various models for predicting the composite's macroscopic elastic constants from the properties of its constituents. The materials chosen for this investigation were alumina continuous fibers on the one hand and alumina and SiC short fibers on the other hand, all embedded in an aluminum alloy matrix. In addition, some indications have been obtained experimentally for the acoustoelastic effect in the composite. 相似文献
3.
Quenching with gases rather than oil or other liquid media has the advantages of reducing the risks concerning health and environment, while simultaneously homogenizing the quenching results and minimizing distortion due to a wide range of possible process parameter variations and the pure convective heat transfer. In this contribution, a coupled solution for increasing homogenization of quenching results within high pressure gas quenching will be presented. In the first stage, an experimental test facility was set up for flow investigations and in the second stage a numerical simulation model was generated. The numerical and experimental results of the flow through the chamber were compared for several boundary conditions. Finally, after complete verification of the simulation, the model may be used to assist in parameter variation for optimization of homogeneous high pressure gas quenching. 相似文献
4.
5.
高硅奥氏体不锈钢由于高含量硅元素的加入使其具有优异的耐高温腐蚀性能和较低的成本,在制酸行业有着潜在的应用价值。然而,该合金中高含量硅元素的加入会促进凝固过程中溶质再分配,进而造成显著的元素偏析,最终导致合金内部产生枝晶组织和大量的有害相。对铸锭组织进行均匀化处理能够有效消除枝晶与元素偏析,促进析出相回溶和枝晶消融,从而改善材料的热塑性,有效应对热变形开裂问题。因此,采用金相显微镜(OM)、扫描电镜能谱分析(SEM/EDS)、电子探针(EPMA)、JMatPro软件计算等方法,研究了实验室条件下制备的5%Si高硅奥氏体不锈钢铸锭的显微组织和元素分布状态,通过残余偏析指数、扩散动力学计算并结合均匀化处理试验验证,最终确定了5%Si高硅奥氏体不锈钢合理的均匀化处理工艺。结果表明,5%Si高硅奥氏体不锈钢凝固过程中钼元素偏析最为严重,通过残余偏析指数模型计算得到的均匀化动力学方程可用来指导该成分合金的均匀化处理工艺;5%Si高硅奥氏体不锈钢经过1 150 ℃×12 h均匀化处理后,铸锭内枝晶消融,元素偏析基本消除,析出相与铁素体回溶到基体中,合金转变为全奥氏体组织,热塑性得到改善;当加热温度达到1 250 ℃时,合金出现过烧现象,晶界开始熔化。 相似文献
6.
HOMOGENIZATION TREATMENT OF Mg-Al-Zn(MM)MAGNESIUM ALLOY INGOTS 总被引:2,自引:0,他引:2
K. Yu W.X. LiCollege of Materials Science Engineering Central South University Changsha China 《金属学报(英文版)》2002,15(6):545-550
The Mg-Al-Zn series AZ31 and AZ31 MM alloys are homogenized at 673, 723 and 753K respectively. The hardness of alloy ingots at different heat-treated states is measured and the micro structures are observed. The optimum annealing temperature is 723K and the time is 12h. 相似文献
7.
We have investigated the axial distribution of the liquid phase in a three-phase fluidized bed in which the particles were glass beads of two different diameters, 710-850 μm and 2 mm. Two methods were used to reduce the axial heterogeneity and homogenize the bed: the use of packing elements and the addition of a small quantity of a high molecular weight polymer. The use of packing elements was shown to be very efficient in controlling phases distribution in the bed. The packing consisted of 1 mm thick steel horizontal plates punched and stretched to obtain parallelogram-shaped openings. The addition of a high molecular weight polyisobutylene (BASF Oppanol B246, Mu, =6.15 Lo6) on the phase distribution was also studied. Low polymer concentrations up to 397 ppm (based on the liquid phase) were investigated. The addition of the polymer reduced bubble coalescence and allowed for a better distribution of the phases. 相似文献
8.
Guo-jun Wang ) Bai-qing Xiong) Yong-an Zhang) Zhi-hui Li) Pei-yue Li) ) State Key Laboratory for Fabrication Processing of Nonferrous Metals General Research Institute for Nonferrous Metals Beijing China ) Northeast Light Alloy Co. Ltd. Harbin China 《北京科技大学学报(英文版)》2009,16(4):427-431
The microstructure of the as-cast 2D70 aluminum alloy and its evolution during homogenization were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analysis. The results indicate that the microstructure of the as-cast 2D70 aluminum alloy mainly consists of the dendritic network of aluminum solid solution and intermetallic compounds (Al2CuMg, Al2Cu, Al9FeNi, Cu2FeAl7... 相似文献
9.
The process parameters of atmospheric plasma spraying (APS) influence the coating formation and properties of partially yttria
stabilized zirconia (PYSZ) thermal barrier coatings (TBC). Simulations can be used to investigate this dependency and to design
the coating process for a targeted production of TBCs. A whole process simulation was realized by modeling the linked subprocesses:
plasma torch, plasma free jet, powder particles characteristics, and coating formation. The coating formation can be described
by model approaches with different physical assumptions and geometric scales. One approach is the simulation of single powder
particles hitting the substrate surface. An alternative macroscale finite element model (FEM) model approach is applied in
the coating formation simulation. A group of particles is pooled in a splash that is dependent on the precalculated particle
distribution in front of the substrate. A third modeling approach is applied to calculate effective mechanical and thermodynamical
properties of coatings dependent on the experimentally obtained or calculated microstructure of the PYSZ TBC, which is based
on different homogenization methods. The application of three simulation approaches in the whole process simulation of APS
is discussed; advantages and disadvantages are elucidated. Results based on simulation and experiments are presented for a
variation of process parameters. Missing links in the multiscale approach are detected to make suggestions for future modeling
and simulation work.
This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials
Park, OH, 2006. 相似文献
10.
为更有效地研究具有周期性微观结构的非均质材料平面应变问题,用基于Cosserat理论的渐进均匀化方法得到微观结构对非均质材料有效性能的影响情况.计算结果表明,单胞内夹杂体的形状对有效杨氏弹性模量、有效泊松比、有效Cosserat弹性常数和有效材料特征长度有影响,并且随着夹杂体与单胞体积比的增大而影响明显. 相似文献