脉冲磁场对Al-6.15Zn-1.41Mg-1.45Cu合金双级时效组织和性能的影响

将Al-6.15Zn-1.41Mg-1.45Cu合金在477℃固溶1 h后,基于脉冲磁场对Al-6.15Zn-1.41Mg-1.45Cu合金进行双级时效处理,通过改变时效时间,且与常规双级时效组织和性能对比分析,研究脉冲磁场对Al-6.15Zn-1.41Mg-1.45Cu合金时效过程中析出相和力学性能的影响,并结合动力学分析Al-6.15Zn-1.41Mg-1.45Cu合金在脉冲磁场双级时效过程中析出相加速析出的扩散机制。采用SEM观察Al-6.15Zn-1.41Mg-1.45Cu合金析出相和拉伸断口形貌,并进行力学性能测试。结果表明,脉冲磁场在Al-6.15Zn-1.41Mg-1.45Cu合金经时效过程中,提高扩散系数,提高析出相的形核率,使得时效后,基体中出现弥散细小的析出相。经脉冲磁场双级时效处理(121℃×90 min+177℃×60 min)后,抗拉强度为495.43 MPa,硬度为156.3 HV5,相比于常规的双级时效处理,抗拉强度提升20.83%,硬度提升17.89%,时效保温时间缩短87.5%。     

磁场对铝合金相变的影响

研究了在Al-4．5Cu、Al-4．0Cu-4．0Zn-0．8Mg合金凝固及均匀化后的冷却过程中,施加磁场对合金组织与热处理后性能的影响,结果表明,磁场能抑制θ相自α相固溶体的析出,从而减少θ相的数量,增大α相的固溶度, 并改变θ相的形态与分布。淬火时施加磁场,使合金时效后的强度和塑性有所提高。     

磁场对铝合金相变的影响

研究了在Al-4．5Cu、Al-4．0Cu-4．0Zn-0．8Mg合金凝固及均匀化后的冷却过程中，施加磁场对合金组织与热处理后性能的影响，结果表明，磁场能抑制θ相自α相固溶体的析出，从而减少θ相的数量，增大α相的固溶度，并改变θ相的形态与分布。淬火时施加磁场，使合金时效后的强度和塑性有所提高。     

脉冲磁场对Al-12.6Si-1Cu合金组织的影响

研究了脉冲磁场下不同的磁场强度和脉冲频率对Al-12.6Si-1Cu合金初生Si和共晶Si组织的影响。在脉冲磁场强度不变的情况下,研究了脉冲频率对共晶Al-Si合金初生Si组织及共晶Si组织的影响。结果表明,随着脉冲频率由0.5Hz增加到2Hz,Al-12.6Si-1Cu合金中初生Si组织和共晶Si组织明显得到细化;当脉冲磁场频率由2Hz继续增加到5Hz时,Al-12.6Si-1Cu合金中初生Si组织和共晶Si组织反而变得粗大。在脉冲磁场的频率为2 Hz的前提下,改变脉冲磁场的强度,结果发现,随着脉冲磁场的强度从5×104 A/m增加到4×105 A/m,Al-12.6Si-1Cu合金中初生Si组织和共晶Si组织得到细化;当脉冲磁场强度由4×105 A/m增加到7×105 A/m时,Al-12.6Si-1Cu合金中初生Si组织和共晶Si组织变得粗大。磁场强度的变化对初生Si及共晶Si影响大于脉冲频率的影响。     

电磁场对共晶Al-2%Fe合金凝固组织的影响

在共晶Al-2%Fe合金凝固过程中分别施加旋转磁场和脉冲磁场,检测了未施加和施加磁场的合金凝固后的宏观和微观组织,以研究电磁场对合金凝固组织的影响。结果表明:未施加电磁场凝固的共晶Al-2%Fe合金的组织较粗大,Al_3Fe相为针状和"X"状;施加旋转磁场凝固的合金组织明显细化,由于受到电磁力的作用,使"X"形Al_3Fe相破碎成针状,并在铸型壁富集,形成大块状Al_3Fe相;施加脉冲磁场凝固的合金,铸型壁的激冷晶和树枝晶由于电磁力的作用而破碎,在铸锭中心形成柱状晶和细小的等轴晶。     

脉冲电场对Al-4%Cu合金固溶组织及固溶工艺的影响

采用电脉冲处理技术作用于Al-4%Cu合金的固溶过程中,能够明显改善Al-4%Cu合金的显微组织,使时效析出过程中相界和品界处的低熔点相含量明显减少,基体中的强化相(CuAl_2)含量明显增多,并且分布更加弥散均匀.同时还能够显著优化Al-4%Cu合金的热处理工艺.在固态相变经典形核理论的基础上,讨论了其作用机理.     

过滤对铝合金凝固过程及其凝固组织的影响

本文用热分析对比法研究了过滤对Al-5%Si、Al-12%Si、Al-20%Si、Al-5%Cu、Al-6%Zn合金凝固过程和凝固组织的影响规律。过滤改变这些合金的凝固参数,加大这些合金的过冷度,缩短合金的凝固时间。过滤使Al-5%Si、Al-5%、CuAl-6%Zn合金的宏观组织粗化,使Al5%Cu合金的微观组织细化。     

方波脉冲电流对Al-Cu合金凝固组织的影响

针对单极方波脉冲电流幅值对Al-Cu合金凝固组织的影响进行了试验研究。结果表明,脉冲电流对亚共晶Al-5Cu和过共晶Al-50Cu合金的凝固组织和初生相有明显细化作用,这主要是由于方波脉冲电流频域较宽,高次波的能量衰减较慢,对凝固系统所做的有效功值较高。由于电流及感生磁场的不均匀性而产生的磁场梯度漂移和磁力线曲率漂移,使得过共晶Al-50Cu合金中Al3 及Cu 离子沿磁场方向迁移,在脉冲电场作用下,促使初生相CuAl2沿磁场方向优势生长。     

脉冲磁场对TC4合金时效过程中析出相的影响

将脉冲磁场施加在TC4钛合金时效过程中,分析脉冲磁场对TC4时效后显微组织及力学性能的影响.通过引入扩散理论,探究脉冲磁场在时效过程中对析出相的影响.结果 表明,经过脉冲磁场处理后,显微组织中的析出相数量明显增多,尺寸变小,且分布更加弥散.外加脉冲磁场时效0.5 h相较于未施加磁场时效4h,抗压强度增加了35 MPa,...     

脉冲磁场对焊缝凝固组织的影响

以AI - 4.5Cu低温合金作为焊材模拟工业生产中大壁厚钢板焊接过程,施加脉冲磁场作为细化焊缝区晶粒的外场作用源,研究了不同脉冲磁场施加方式、励磁线圈结构、脉冲磁场参数变化以及凝固工艺参数对焊缝凝固组织的影响.试验结果表明,施加脉冲磁场能改善焊缝凝固组织,使柱状晶向等轴晶转化,细化焊缝区晶粒;特别在E形线圈横向脉冲磁场作用下的焊缝凝固组织细化效果更为明显.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

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.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.