电极感应熔化气雾化粉末特性及液滴尺寸影响因素的研究

对电极感应熔化气雾化(electrode induction melting gas atomization,EIGA)工艺制备的镍基高温合金粉末的物理特性,凝固组织以及内部元素分布进行研究;理论分析了EIGA制粉一次雾化过程中液滴尺寸的影响因素;根据对流换热原理计算了该工艺中不同尺寸粉末的冷却速率。结果表明:EIGA粉末以近球形为主,霍尔流速为13.4 s/50 g,D90=121.5μm。粉末表面和内部凝固组织显示,随着粉末尺寸的增大,组织均由微晶向胞状晶和树枝晶转变。同时颗粒表面组织之间的间隙不断加深,粉末光滑度下降。在雾化气压为4 MPa条件下,粉末尺寸与冷却速率的关系为:■。粉末内部没有明显的成分偏析现象,但晶轴和晶间的元素分布略有差别。晶轴上Ni、Al、Co、C元素含量较晶间高,晶间的Ti、Mo、Cr、Nb元素含量更高。     

雾化气体和冷却速率对镍基合金粉末凝固特性的影响（英文）

分别采用氩气和氮气作为雾化介质,制备得到镍基合金粉末。利用扫描电镜分析2种气体雾化的粉末表面形貌及凝固组织特征。基于牛顿冷却模型,对雾化粉末冷却速度和飞行速度进行数值计算。结果表明:冷却速率决定了凝固微观组织形貌。在较低的冷却速率下,2种气体雾化粉末均呈现发达的枝晶组织,而随着冷却速率的增大,氩气雾化粉末呈现欠发达的枝晶和胞晶混合组织。而氮气雾化粉末仅呈现胞晶组织。不同粒径氩气雾化粉末冷却速率在1.0×10~5~4.24×10~6 K·s~(-1),氮气雾化粉末在1.0×10~5~4.8×10~6 K·s~(-1)。冷却速率随粉末直径增加而减小。在快速凝固过程中,Cr,Co,W,Ni和Al等元素仍沿晶轴偏析,而Ti元素沿晶间偏析。     

等离子旋转电极雾化FGH95高温合金粉末颗粒凝固组织特征

对等离子旋转电极雾化(PREP)FGH95高温合金粉末颗粒凝固组织特征进行研究,并用数值分析方法计算了FGH95合金粉末凝固过程中冷却速率与粉末粒度之间的关系,结果表明:粉末颗粒表面凝固组织主要是树枝晶和胞状长大晶,随着粉末颗粒尺寸的减小,内部凝固组织由树枝晶为主逐渐转变为以胞状晶及微晶组织为主,冷却速率与粉末粒度之间的关系为T=2.267×109d-1.649,由此得出FGH95合金二次枝晶臂距与冷却速率之间的关系为S=36.2T-0.24.     

不同冷却速率对GH4151高温合金定向凝固组织及元素偏析的影响

为了进一步降低合金凝固偏析程度和优化真空自耗冶炼(VAR)工艺,利用液态金属冷却法(LMC)对GH4151合金进行定向凝固实验,采用光学显微镜、扫描电镜及电子探针等研究了冷却速率对GH4151合金定向凝固组织及元素偏析的影响。结果表明：随着冷却速率的增加,一次枝晶间距λ₁及二次枝晶间距λ₂均逐渐减小,两者与冷却速率间满足相似的函数关系。而且,枝晶干及枝晶间γ′相尺寸也随冷却速率的增加逐渐减小,组织均匀性提高。对凝固组织元素成分分布的电子探针分析表明：GH4151合金主要偏析元素为W、Nb、Ti,偏离程度在20%以上,且3种元素显微偏析程度均随冷却速率的增加而加重,原因在于随着冷却速率增加,凝固前沿固相层可供溶质扩散的时间减少,扩散效果减弱。     

球形TC4粉末的气雾化制备、表征及间隙元素控制

利用水冷铜坩埚熔炼、高纯氩气雾化技术制备出高品质球形TC4合金粉末。将石墨导流管的内壁用Y_2O_3与无水乙醇配比的涂料进行涂覆,分析其对雾化粉末间隙元素的影响,总结气雾化粉末的间隙元素来源及控制建议,并对不同粒度粉末的显微组织进行表征。结果表明:石墨导流管内壁在无涂层的情况下,雾化粉末的碳含量较大;而导流管内壁的Y_2O_3涂层能有效降低碳对钛合金污染的风险;粉末间隙元素含量随着粒径的减小而增大;粒径较大粉末的表面为胞状晶组织,而小尺寸粉末表面光滑且无明显结晶组织;由于快速凝固的原因,粒径较大粉末的内部主要由α相胞晶和针状马氏体α′相组成,小粒径粉末的内部组织明显细化,全部为蜂窝状的胞状晶组织。     

超音速电弧喷射雾化银合金熔滴的传热与冷却

对超音速电弧喷射雾化Ag-Cu共晶型和Ag-Ni、Ag-Fe偏晶型合金雾化熔滴的传热与冷却进行了分析.考虑到熔滴冷却过程中, 表面热传导存在上限, 内部存在一定热阻, 熔滴冷却应为近似牛顿冷却方式, 在前人工作基础上, 对牛顿冷却方式的换热系数和冷却速率的表达公式进行了经验修正, 并用其它冷却速率测量方法进行了验证;计算了Ag合金雾化熔滴的换热系数和冷却速率, 结果显示, 超音速电弧喷射雾化快速凝固Ag合金粉末的冷却速率达到105～7K/s, 表明超音速电弧喷射雾化工艺的冷却速率比常规气雾化法高得多, 是制备高性能快速凝固合金粉末的新方法.     

雾化气体和冷却速度对镍基合金粉末凝固特性的影响

镍基合金粉通过氩气雾化和氮气雾化制得。利用扫描电镜及其借助EDS能谱仪研究了雾化粉末的凝固微观结构特性。基于牛顿冷却模型,计算了雾化融滴的冷却速度和飞行速度。计算结果表明,雾化介质和融滴尺寸对冷却速度有影响,冷却速度也影响粉末的微观结构。对于氩气雾化粉,发达的枝晶结构在较低的冷速下获得;在较高的冷却速度下,得到混合的微观结构（枝晶和包晶）。对于氮气雾化粉,较低的冷速下得到枝晶;在较高的冷速下得到包晶。通过理论计算,氩气雾化粉末的冷却速度是10000K/s到424000 K/s,氮气雾化粉的冷却速度是10000K/s到480000 K/s。随着融滴尺寸的减小,两种雾化粉末的冷却速度则逐渐增加。元素Cr, Co, W, Ni 和 Al主要集中于晶轴,然而Ti主要集中于枝晶区域。     

超音速电弧喷射雾化制备的非互溶Ag-10Ni合金粉末的凝固特征

采用超音速电弧喷射气雾化制粉设备制备了难固溶Ag-10Ni合金粉末。研究了粉末粒度分布、形貌及凝固组特征，并对雾化熔滴的冷却速率及过冷度、凝固组织的凝固次序、形成机制进行了分析。结果表明：粉末分散性好、粒度主要集中在20pm～45μm、平均粒度32μm、形貌主要为球形和近球形；粉末颗粒凝固组织为富Ag基体＋弥散分布于基体中的细Ni相＋位于芯部的大直径初晶富Ni相，在大直径初晶富Ni相中弥散分布析出Ag相；富Ag基体的凝固组织为树枝晶组织，小颗粒粉末（〈20μm）枝晶间距小于0．2μm。     

冷却速度对气雾化非平衡Al-27%Si合金粉末组织形貌特征的影响

采用快速凝固气体雾化技术制备Al-27%Si合金粉末,利用对流传热原理计算合金粉末的冷却速度,采用扫描电镜(SEM)观察分析不同粒度合金粉末的形貌。结果表明:快速凝固气体雾化的冷却速度介于103~106 K/s之间,对合金粉末形貌组织有较大影响。该合金粉末中细小初晶Si相和共晶Si相均匀弥散分布在α-Al基体中,且Si颗粒尺寸随粉末尺寸减小而减小。通过测定合金粉末二次枝晶间距,结合冷却速度与二次枝晶间距之间的经验公式,能较好地预测实验结果。     

冷却速率对Mg-Gd-Y-Zr合金凝固组织的影响

通过改变凝固过程中的冷却速率,研究了冷却速率对Mg-Gd-Y-Zr合金凝固组织与成分微观偏析的影响.随冷却速率提高,合金组织明显细化,初生相形貌由粗大等轴枝晶逐渐向细小树枝晶转变,合金凝固过程中形核率增加,合金晶粒尺寸逐渐减小;冷却速率的提高可以降低溶质元素的扩散速率,从而增加合金元素在枝晶干中的固溶度,减轻凝固过程中合金元素Gd与Y的微观偏析,同时使凝固过程中形成的共晶减少,共晶组织分布更加弥散、均匀.     

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.     

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.     

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。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.