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991.
采用金相显微镜、SEM、EDAX等试验方法,研究添加Ti、B、Sr、RE元素细化及变质对A356铝合金显微组织的影响,得出RE的添加并未与合金中的Mg形成高Mg含量化合物,Mg的分布仍很均匀,同时含铁相得到细化;对于0.10%Ti细化的A356铝合金,RE的添加使二次枝晶间距明显减小;0.01%Ti与0.03%B联合细化对A356铝合金的细化作用明显优于0.10%Ti的细化作用,晶粒为细小等轴晶,且Al-Fe-Si-Mg、Al-Si-RE相得到明显的细化;Ti、B、Sr、RE联合细化及变质的合金获得了最佳的硅颗粒变质效果。 相似文献
992.
综述了TiN/Al2O3,AlN/Al2O3以及(TiN,AlN)/Al2O3复合材料的研究现状。并指出颗粒增韧是复相陶瓷材料增韧最简单的方式之一,其中纳米复合、纳微米复合、多相复合是实现颗粒增韧的有效途径。在复相陶瓷的制备中,原位反应烧结是很有希望的技术,可以直接在基体中生成弥散分布的超细第二相颗粒,而使复合材料的性能大幅度提高。 相似文献
993.
在硫酸盐-氯化物溶液体系中采用电沉积法制得了光亮Ni-Fe软磁合金箔,研究了n(Ni^2+)/n(Fe^2+)摩尔比,电流密度,镀液pH,镀液温度对电沉积Ni-Fe合金箔的铁含量的影响规律,确定了最佳工艺条件.验证性实验结果表明,在最佳工艺条件下制备的Ni-Fe合金箔是纳米晶合金,其Ni,Fe含量分别为80.4%(质量)和19.6%(质量).这种合金箔外观平整、致密,具有明显的层状结构,其饱和磁通密度(Ms)为94.23emu/g,剩余磁通密度(Mr)为4.33emu/g,矫顽力(Hc)为5.08Oe. 相似文献
994.
995.
The α alloy Ti-2Al-2.5Zr and near α alloy Ti-4Al-2V were hydrogenated to various levels. The morphology,orientation relation (OR), and habit plane of the hydrides were studied by means of transmission electron microscopy (TEM). It was found that in the two alloys most of the precipitates are δ-hydrides which have fcc structure with the lattice parameter a = 0.44 nm. Two basic orientation relationships and habit planes of the precipitates are determined. Twin structure was observed in both alloys. 相似文献
996.
Preparation, thermal stability, and magnetic properties of Fe---Co---Zr---Mo---W---B bulk metallic glass 总被引:1,自引:0,他引:1
D.Y. Liu W.S. Sun A.M. Wang H.F. Zhang Z.Q. Hu 《Journal of Alloys and Compounds》2004,370(1-2):249-253
A bulk metallic glass (BMG) cylinder of Fe60Co8Zr10Mo5W2B15 with a diameter of 1.5 mm was prepared by copper mould casting of industrial raw materials. The amorphous state and the crystallization behavior were investigated by X-ray diffraction (XRD). The thermal stability parameters, such as glass transition temperature (Tg), crystallization temperature (Tx), supercooled liquid region (ΔTx) between Tg and Tx, and reduced glass transition temperature Trg (Tg/Tm) were measured by differential scanning calorimetry (DSC) to be 891, 950, 59 K, and 0.62, respectively. The crystallization process took place through a single stage, and involved crystallization of the phases -Fe, ZrFe2, Fe3B, MoB2, Mo2FeB2, and an unknown phase, as determined by X-ray analysis of the sample annealed for 1.5 ks at 1023 K, 50 K above the DSC peak temperature of crystallization. Mössbauer spectroscopy was studied for this alloy. The spectra exhibit a broadened and asymmetric doublet-like structure that indicated paramagnetic behavior and a fully amorphous structure. -Fe was found in the amorphous matrix for a cylinder with a diameter of 2.5 mm. The success of synthesis of the Fe-based bulk metallic glass from industrial materials is important for the future progress in research and practical application of new bulk metallic glasses. 相似文献
997.
5182铝合金板温成形工艺及摩擦学特性的研究 总被引:3,自引:0,他引:3
通过对5182铝合金板的室温及高温力学性能的实验研究与分析,提出了5182铝板的温成形工艺。实验研究了工艺参数对5182可成形性能的影响,并分析了成形过程中材料表面化学性能、表面几何形貌和润滑状态等因素对摩擦学特性的影响,最后进行了仿车门零件的成形实验和有限元模拟。 相似文献
998.
Désirée Risch Alexander Brosius Matthias Kleiner 《Journal of Materials Engineering and Performance》2007,16(3):327-330
Electromagnetic sheet metal forming is a high speed forming process using pulsed magnetic fields to form metals with high
electrical conductivity such as aluminum. Thereby, workpiece velocities of more than 300 m/s are achievable, which can cause
difficulties when forming into a die. The kinetic energy, which is related to the workpiece velocity, must be dissipated in
a short time slot when the workpiece hits the die; otherwise undesired effects, for example rebound can occur. One possibility
to handle this shortcoming is to locally increase the stiffness of the workpiece. A modal analysis is carried out in order
to determine the stiffness of specific regions of the workpiece so that an estimation concerning the feasibility of the desired
geometry is possible in advance without doing cost and time consuming experiments. Thereby, the desired geometry of the workpiece
will be fractionized in significant sectors. This approach has to define the internal force variables acting on the cutting
edge, which are required to constrain the numerical model. Finally, a method will be developed with the objective of calculating
the stiffness of each sector. The numerical results will be verified by experiments.
This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati,
OH, October 15-19, 2006. 相似文献
999.
Electroplated CBN grinding wheels are manufactured with a single layer of abrasive grains. The grinding performance of these plated wheels changes significantly as the wheel wears down. The present investigation was undertaken to understand the transient grinding behavior with electroplated CBN wheels in order to provide a logical basis for process control. In this paper, particular attention is directed to the effect of wheel wear and operating parameters on grinding of a nickel alloy. Wheels were worn to various stages and then used to perform grinding tests under various grinding conditions to measure grinding forces and power and to produce ground specimens. Based on models for grinding with conventional aluminum oxide wheels, a power model for grinding of a nickel alloy with plated CBN wheels was established and validated. Microscopic observations of the ground specimens reveal that thermal damage in the form of a White Etch Layer (WEL) appears only when grinding with a worn wheel under conditions that lead to high temperatures. 相似文献
1000.
Nanocrystallized Cr1−xAlxN films with various Al contents (0 to 68 at.%) were deposited by pulsed closed field unbalanced magnetron sputtering (P-CFUBMS). The effects of aluminum content on the microstructure, mechanical and tribological properties of the Cr1−xAlxN films have been investigated. It was found that the hardness and elastic modulus of Cr1−xAlxN films increased with increasing Al contents in the films and reached the highest value of 36 GPa and 370 GPa, respectively, at an Al content of 58.5 at.%. Addition of Al beyond 64.0 at.% resulted in a change in crystal structure from B1 cubic to B4 hexagonal phase. The wear resistance improved gradually with the increase of Al in the Cr1−xAlxN films. A combination of the abrasive and adhesive wear mechanism was proposed based on the SEM and EDS analysis of the wear track. The steady state dry coefficient of friction measured against a WC ball for the Cr1−xAlxN films were in the range of 0.36-0.55, and the wear rate was in the 10− 6 mm3 N− 1 m− 1 range. 相似文献