C/C复合材料与TC4钎焊接头的组织与断裂形式分析

在钎焊时间10 min,钎焊温度820～900℃的条件下,采用AgCu钎料对C/C复合材料和TC4进行了钎焊试验.利用扫描电镜、X射线衍射分析仪、EDS能谱分析仪对接头的界面组织及断口形貌进行了研究.结果表明,C/C复合材料与TC4连接接头的界面结构为C/C复合材料/TiC C/TiCu/Ag(s.s) Cu(s.s) Ti3Cu4/Ti3Cu4/TiCu/Ti2Cu/Ti2Cu Ti(s.s)/TC4.由压剪试验测得的接头抗剪强度可知,在钎焊温度850 ℃,保温时间10 min的钎焊条件下,接头获得的最高抗剪强度达到38 MPa.接头的断口分析表明,接头的断裂位置与被连接处碳纤维方向和钎焊温度有关.当碳纤维轴平行于连接面时,断裂发生在复合材料中.当碳纤维轴垂直于连接面时,若钎焊温度较低,断裂发生在C/C复合材料/钎料界面处;若钎焊温度较高,断裂主要发生在C/C复合材料/钎料界面和钎料/TC4界面处.     

AgCu钎料钎焊TC4钛合金与QCr0.8铬青铜接头界面结构及性能

采用AgCu28钎料实现了TC4钛合金与QCr0.8铬青铜的真空钎焊,利用SEM, EDS以及XRD等分析方法确定TC4/AgCu/QCr0.8接头的典型界面结构为TC4钛合金/CuTi +Cu3Ti2 +CuTi2/Ag(s,s) +Cu4Ti/Ag(s,s)+Cu(s,s)/QCr0.8铬青铜. 研究了工艺参数对接头组织和性能的影响. 结果表明,随着钎焊温度和保温时间的增加,钎缝中银铜共晶组织减少,钛铜化合物增多. 接头抗剪强度随钎焊温度的升高先增加后降低,在钎焊工艺参数为890 ℃/0 min时,获得最大抗剪强度449 MPa.保温时间的延长使得接头脆性钛铜化合物增多,接头性能下降,因此随保温时间延长接头抗剪强度显著降低.     

C／C复合材料与TC4合金钎焊接头的组织与性能分析

在钎焊时间3～30min，钎焊温度860-1000℃的条件下，采用AgCuTi钎料对C／C复合材料和TC4合金进行了钎焊试验。利用扫描电镜及EDS能谱分析的方法对接头的界面组织及断口形貌进行了研究。结果表明，接头界面结构为C／C复合材料／TiC＋C／TiCu＋TiC／Ag（s．s）＋Ti3Cu4＋TiCu／Ti3Cu4／TiCu／Ti2Cu／Ti2Cu＋Ti（s．s）／TC4。由压剪试验测得的接头抗剪强度结果可知，在钎焊温度910℃，保温时间10min的条件下，接头获得的最高抗剪强度为25MPa。接头的断口分析结果表明，接头断裂的位置与被连接界面的碳纤维方向有关，当碳纤维轴平行于连接面时，断裂发生在复合材料中；当碳纤维轴垂直于连接面时，断裂主要发生在复合材料与钎料的界面处。     

TiZrNiCu钎料钎焊石墨与TC4接头组织与力学性能研究

在钎焊时间为60～1500s,钎焊温度1163～1273K的条件下,采用TiZrNiCu钎料对石墨和TC4钛合金进行了钎焊试验。利用扫描电镜及能谱仪对接头的界面组织进行了研究。结果表明,接头界面结构为石墨/TiC/(Ti,Zr)2(Cu,Ni)/Ti(s.s)+(Ti,Zr)2(Cu,Ni)/TC4。以抗剪强度评价石墨和TC4钛合金接头的力学性能,发现当钎焊温度为1193K,保温时间为300s时,接头抗剪强度最高,为15MPa。     

Ti3Al与316L不锈钢的真空钎焊工艺

采用Ag-Cu钎料对Ti_3Al与316L不锈钢进行真空钎焊连接,通过扫描电镜、能谱分析仪和X射线衍射仪分析了接头界面结构并对其形成机理进行了分析,同时,研究了钎焊温度对接头界面组织以及抗剪强度的影响。结果表明,在固定保温时间为5 min时,接头的抗剪强度先随着钎焊温度的升高而增大,当钎焊温度为800℃时,接头抗剪强度达到最大值为343 MPa,当钎焊温度进一步升高时,接头抗剪强度会呈现降低趋势。接头的典型界面结构为Ti_3Al/Al Cu_2Ti+Cu_2Ti+Cu(s,s)+Ag(s,s)+Cu Ti+Fe_2Ti/316L不锈钢。     

SiO2玻璃陶瓷与TC4钛合金的活性钎焊

分别采用活性钎料AgCuTi和TiZrNiCu对SiO2陶瓷和TC4钛合金进行了钎焊连接,使用扫描电镜和X射线衍射等手段对接头的界面组织和力学性能进行了研究.结果表明,采用两种钎料均能够实现对SiO2陶瓷和TC4钛合金的连接;SiO2/TiZrNiCu/TC4接头的典型界面为SiO2/Ti2O+Zr3Si2+Ti5Si3/(Ti,Zr)+Ti2O+TiZrNiCu/Ti基固溶体/TiZr-NiCu+Ti基固溶体+Ti2(Cu,Ni)/TC4;SiO2,AgCuTi/TC4接头的典型界面为SiO2/TiSi2+Ti4O7/TiCu+Cu2Ti4 O/Ag基固溶体+Cu基固溶体/TiCu/Ti2Cu/Ti+Ti2 Cu/TC4.当钎焊温度为880℃和保温时间为5 min时,SiO2/TiZrNiCu/TC4接头的最高抗剪强度为23 MPa;当钎焊温度为900℃和保温时间为5 min时,SiO2/AgCuTi/TC4接头的最高抗剪强度为27MPa.     

复合粉末中间层钎焊SiO2 陶瓷与TC4合金的接头组织与性能

采用46.4%Ag-18.0%Cu-35.6%Ni(质量分数)复合粉末中间层实现了SiO2陶瓷和TC4钛合金的良好钎焊.使用扫描电镜、能谱分析和X射线衍射等方法对钎焊接头的界面组织和力学性能进行了研究.结果表明,SiO2陶瓷和TC4钛合金的连接接头成形良好,SiO2陶瓷/Ag-Cu/Ni/TC4钛合金钎焊接头的界面结构为:SiO2/Ti4O7+TiSi2/Ti2Cu+Ti2Ni/α-Ti+Ti2Cu+Ti2Ni过共晶组织/α-Ti+Ti2Cu+Ti2Ni过共析组织/α-Ti/TC4.当钎焊温度为970 ℃、保温时间为30 min时,使用Ag-Cu/Ni粉末中间层钎焊SiO2陶瓷与TC4钛合金的接头达到最高抗剪强度38 MPa.     

钎焊温度对TC4/Ti60接头组织及性能的影响

为研究钎焊温度对TC4/Ti60接头组织及力学性能的影响,采用纯铜箔作为中间层对TC4与Ti60合金进行接触反应钎焊,钎焊温度范围为970~1 010℃.采用SEM,EDS,XRD,拉剪试验对接头组织及力学性能进行研究.结果表明,接头的典型界面组织为TC4/α-Ti+Ti_2Cu/Ti_2Cu/Ti Cu/Ti_2Cu/α-Ti+Ti_2Cu/Ti60.随着钎焊温度的升高,基体侧的反应扩散层厚度增加,钎缝厚度及Ti-Cu金属间化合物含量逐渐减少,钎缝成分趋于均匀化.接头抗剪度随钎焊温度的升高先增加后减少,当钎焊工艺为1 000℃保温10 min时,接头抗剪强度最高为130 MPa.断口分析表明,接头断裂于钎缝与扩散反应层之间,断裂方式为准解理断裂.     

AgCu+nano-Al_2O_3复合钎料钎焊TC4合金与Al_2O_3陶瓷:界面结构及接头性能

通过向Ag Cu共晶钎料中添加nano-Al2O3增强相(2%,质量分数)并采用高能球磨的方法获得了Ag Cu+nano-Al2O3复合钎料(Ag Cu C钎料)。采用Ag Cu C钎料实现了TC4合金与Al2O3陶瓷的高质量钎焊连接,确定了TC4/Ag Cu C/Al2O3钎焊接头的典型界面组织结构为:TC4/α-Ti+Ti2Cu扩散层/Ti3Cu4层/Ag(s,s)+Ti3Cu4+Ti Cu/Ti3Cu4层/Ti3(Cu,Al)3O层/Al2O3。Nano-Al2O3的添加抑制了钎缝中连续的Ti-Cu化合物层的生长,同时在钎缝中形成了颗粒状Ti-Cu化合物相增强的Ag基复合材料,改善了钎焊接头的界面组织。随着钎焊温度的升高,各反应层厚度逐渐增加,颗粒状Ti-Cu化合物不断长大,Ag基复合材料组织逐渐细小。当钎焊温度T=920℃,保温时间t=10 min时接头抗剪强度达到最大为67.8 MPa,典型断口分析表明:压剪过程中,裂纹起源于钎角处并沿钎缝扩展后转入Al2O3陶瓷,最终在Al2O3陶瓷母材侧发生断裂。     

Ag-Cu+WC复合钎料钎焊ZrO2陶瓷和TC4合金

采用新型Ag-Cu+WC复合钎料进行ZrO₂陶瓷和TC4合金钎焊连接,探究了接头界面组织及形成机制,分析了钎焊温度对接头界面结构和力学性能的影响. 结果表明,接头界面典型结构为ZrO₂/TiO+Cu₃Ti₃O/TiCu+TiC+W+Ag_(s,s)+Cu_(s,s)/TiCu₂/TiCu/Ti₂Cu/TC4. 钎焊过程中,WC颗粒与Ti发生反应,原位生成TiC和W增强相,为Ti-Cu金属间化合物、Ag基和Cu基固溶体提供了形核质点,同时抑制了脆性Ti-Cu金属间化合物的生长,优化了接头的微观组织和力学性能. 随钎焊温度的升高,接头反应层的厚度逐渐增加,WC颗粒与Ti的反应程度增强. 当钎焊温度890 ℃、保温10 min时,复合钎料所得接头抗剪强度达到最高值82.1 MPa,对比Ag-Cu钎料所得接头抗剪强度提高了57.3%.     

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.