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感应加热对半固态AlSi7Mg合金连铸坯温度场和组织的影响 总被引:5,自引:3,他引:2
研究了电磁感应重熔加热对半固态AlSi7Mg合金铸坯料温度场和组织的影响。结果表明:通过调整加热功率,可使半固态AlSi7Mg合金连铸坯料的温度场均匀一致,保证坯料的径向温差差小于1℃;电磁感应重熔加热的兰固态AlSi7Mg合金连铸坯料中的初生α(Al)组小、圆整、分布均匀,但重熔过程不能改变坯料表层组织中初生αA(l)枝晶的基本形态。 相似文献
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半固态AlSi7Mg合金二次加热工艺与组织转变机制 总被引:18,自引:0,他引:18
采用电阻炉对用电磁搅拌方法制备的半固态AlSi7Mg合金二次加热,结合金相分析研究了半固态组织的转变机制。实验发现,共晶相中的Si相通过向α相中扩散溶解,其形状从片层状断裂成点链状颗粒,并随着温度升高颗粒细化球化。片层越薄,这一过程发生的温度越低,速度越快。Si溶解到一定程度后共晶部分熔化,初生α相形状、尺寸开始变化。树枝状α相和蔷薇花状α相球化,但前者变大,后者变小为原始尺寸的1/2-1/4。近 相似文献
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分别采用双级雾化、超音气体雾化、喷射沉积和金属型铸造等工艺制备了Al-20Si和2024-20Si-5Fe 合金。利用XRD、TEM 和SEM 测试技术分析了制备工艺对合金相组成、α-Al相晶格常数和固溶度的影响。结果表明:当制备工艺的冷却速度达到103 K/s 以上时,β-(Fe2Si2Al9)、CuAl2 和Mg2Si相的析出得到有效抑制;第二相随制备工艺的冷却速度增大而细化,α-Al相的晶格常数减小;Al-20Si合金中硅元素在α-Al中的最大固溶度高达3.209% 。 相似文献
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研究了热处理工艺对定向凝固条件下Al-Si合金共晶组织的影响。通过多级长时间的固溶处理及回火处理,AsSi7.0Mg0.30和AlSi7.0Mg0.3Sr合金中的共晶体体积分散在较快冷却速度时要比慢速冷却时的高,而共晶体中硅粒子的体积分数则有较大幅度的降低。 相似文献
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AlSi7Mg非枝晶合金半固态重熔加热时的组织演变 总被引:15,自引:1,他引:14
研究表明:电磁搅拌的AlSi7Mg非枝晶合金在半固态温区保温时,共晶体首先重熔,团块状α相逐渐演变成球状;保温温度越高,半固态重熔和α相演变过程越快;保温温度过高或保温时间过长时,试样在部分重熔过程中易发生变形。 相似文献
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粉末热锻Al—Si合金 总被引:4,自引:0,他引:4
邱光汉 《中国有色金属学报》1996,6(2):117-120
研究了Al-Si合金粉末热锻密实工艺和合金性能。结果表明,当合金含硅量不超过30%时,锻的密度可达到理论密度的99%以上。合金组织中初晶硅分布均匀,没有针状或大块片状组织出现。添加Cu、Mg的Al-10Si-2Cu-1Mg和Al-15Si-2Cu-1Mg合金性能比相应的Al-Si二元合金明显提高,拉伸强度分别达到184-0324MPA和304-333MPA,布氏硬氏124-128和122-124。 相似文献
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C.J. Sun H.R. Geng Y.S. Shen X.Y. Teng Z.X. Yang 《金属学报(英文版)》2007,20(3):181-186
The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy. 相似文献
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Peng Liu Zhao-Kuang Chu Yong Yuan Dao-Hong Wang Chuan-Yong Cui Gui-Chen Hou Yi-Zhou Zhou Xiao-Feng Sun 《金属学报(英文版)》2019,32(4):517-525
The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests. 相似文献
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《中国铸造》2014,(6):540-541
Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 (hereinafter referred to as FSC 2014) was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers. 相似文献
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LASER CLADDED TiCN COATINGS ON THE SURFACE OF TITANIUM 总被引:3,自引:0,他引:3
Y.L. Yang D. Zhang and H.S. Kou College of Science Northeastern University Shenyang China C.S. Liu College of Material Metallurgy Northeastern University Shenyang China 《金属学报(英文版)》2007,20(3):210-216
Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques. 相似文献
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X80 pipeline steel plates were friction stir welded(FSW) under air, water, liquid CO_2 + water, and liquid CO_2 cooling conditions, producing defect-free welds. The microstructural evolution and mechanical properties of these FSW joints were studied. Coarse granular bainite was observed in the nugget zone(NZ) under air cooling, and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature reduced. In particular, under the liquid CO_2 cooling condition, a dual phase structure of lath martensite and fi ne ferrite appeared in the NZ. Compared to the case under air cooling, a strong shear texture was identifi ed in the NZs under other rapid cooling conditions, because the partial deformation at elevated temperature was retained through higher cooling rates. Under liquid CO_2 cooling, the highest transverse tensile strength and elongation of the joint reached 92% and 82% of those of the basal metal(BM), respectively, due to the weak tempering softening. A maximum impact energy of up to 93% of that of the BM was obtained in the NZ under liquid CO_2 cooling, which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite. 相似文献
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《中国铸造》2014,(3):215-217
China Securities News reported on March 21, 2014: Guangdong Hongtu Wuhan Die Casting Co., Ltd. (Wuhan Hongtu), a wholly owned subsidiary of Guangdong Hongtu Technology (Holdings) Co., Ltd., held a groundbreaking ceremony recently. With the registered capital of 50 million Yuan, Wuhan Hongtu has a total land area of 100,000 square meters and a plant construction area of 72,000 square meters. It is expected to have a production capacity of about 30,000 tonnes of aluminum castings annually after it is put into production. 相似文献
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Z.C. Guo X.Y. Zhu R.D. Xu 《金属学报(英文版)》2007,20(2):111-116
The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE (rare earth)-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with the increase of pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r= 0.8 is higher than that at r= 0.6. 相似文献
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M.E Li G. C. Yang 《金属学报(英文版)》2007,20(4):258-264
Two new classes of growth morphologies, called doublons and seaweed, were simulated using a phase-field method. The evolution of doublon and seaweed morphologies was obtained in directional solidification. The influence of orientation and velocity on the growth morphology was investigated. It was indicated that doublons preferred growing with its crystallographic axis aligned with the heat flow direction. Seaweed, on the other hand, could be obtained by tilting the crystalline axis to 45°. Stable doublons could only exist in a range of velocity regime. Beyond this regime the patterns formed would be unstable. The simulation results agreed with the reported experimental results qualitatively. 相似文献
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Z. Sun S.L. Zheng Y. Zhang 《金属学报(英文版)》2007,20(3):187-192
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process. 相似文献